Screenprint Emulsion-Stencils *Added: Photopolymer and Results!*

[Overmountain]

Alright... Let me say if you are reading this while this preface is still here, the thread isn't done yet... I have a few little tweaks to do before it is 100% there. But, etching stencils have been a constant question lately, so I will go ahead and post what I have... Maybe we can all tweak this out together. My etching machine is also on the fritz, the transformer was apparently shot... Come pay day, that will be fixed.... love working for the government... such a high paying industry...


Ok, so let me begin with thanking JRM Promotions here in my home town. They helped me out quite a bit. They do a lot of screen-printing and were the genesis of this whole thing. I originally was trying to find a better mousetrap. A way to make a long lasting stencil that was cheap, precise, and easy to do at home without much special equipment. The photoreacive films that are offered by a couple of carriers are terrific and really hard to beat for precision and easy of transferring any image or text that you can print from a computer file. But, their shortcomings are the cost and the need for separate developers and a very deft touch when scrubbing away the exposed resist. They also require a negative image and it must be dark dark dark or you won't get the detail or the coverage of the resist that you need.

I was also trying to replace the awkward pin-roll material I was using. I was introduced to this material by Stacy, and have used it quite a bit thanks to access to a dot-matrix printer. Let me say, if you are going to do a series of things, like small tools or restorations that require a specific marking that is available in plain text, like a socket set or something, this stuff is hard to beat. You can quickly whip out a set of alpha-numeric characters that will allow you to etch a series very very quickly. For our purposes, it is possible to trace a printed image on the material using a stylus... (I used the sharp-ish stylus from my kid's Nintendo 3DS...) After tracing the image you are left with a fairly precise image that can be easily etched.

Now, I discovered pretty quickly that screen-printing emulsions sadly weren't going to give me the long lasting stencils I had wanted, like those from Ernie or TUS Tech. They aren't even nearly as resilient as the photo-reactive film from Etch-O-Matic and the like... But, they are cheap. And I mean dirt cheap to make. This makes it appealing all the same and a pretty good option for one off markings that need to be done. Or, just making a whole crap ton of one image at a time... The total cost for emulsion and mesh comes in around $10-12 for enough to do 1-2 yards worth of material. Now, when we are talking about images that are usually less than an inch across and a half inch high, that is a whole lot of stencils. Even when spaced a couple of inches apart. The speedball emulsion (as much as the name 'speedball' goes against everything I usually do...) is about $7 for the emulsion and sensitizer, and the Ryocap sheets can be had for $4 a piece for a 12"x15"ish sheet. Mesh is sold in numerical values of about 80-350. This refers to the thread count per inch square of material. We are going for a sharp image, so the higher the thread count the better. The mesh can be found on ebay, Amazon, etc for just a couple bucks a yard. Or, you can go to a trophy/t-shirt/promotional shop in your area that does screen-printing and ask for scraps and the like. They may just hook you up with enough materials to do what we need to do for free. Again, much like companies that use bulk metals, something less than a couple feet square is scrap to these shops. A cup or two of coffee is more than fair trade for them usually.

Ok, lets get started. First things first, let me say that if you haven't done this before, there WILL BE A LEARNING CURVE. Let this guide as well as the other how to's on the web at least shorten this curve for you... I will cover both methods, raw emulsion and the Ryocap sheets. For both methods, there is one item that is unreasonably expensive... And is the most expensive part of any of these exposure methods, but a little goes a long way thankfully. That part is the printable transparency sheets. Shop around, because there are deals to be found. I also discovered that the sheets listed for laser printers will work with inkjet. The only issue is that the ink won't set up so it can smear. Office Depot want $50 for a pack of these sheets... I found these Apollo brand (a good brand BTW) on ebay for $11 shipped. For 50 sheets that should last me a long long time, that ain't too bad and keeps us in the uber-cheap price point we were aiming for.

First, the raw emulsion. I have since been informed that there are much better emulsions out there. Hopefully someone that does a lot of screen-printing will not only correct my mistakes, but tell of these better emulsions. For the speedball emulsion you will have to build a frame to stretch the mesh on. Simple pine 1"x1" will do, as will a staple gun to hold it together. Not looking for a cabinet here, just a simple frame. If you want, there are professional frames out there, but even the smallest ones are rather pricey for what they are IMHO. Easy enough for us to build our own.

Once the frame is built, we need to stretch the material onto the frame. Again, a staple gun will work nicely for this. Make sure you are stapling on a firm surface. We need the staples to be nice and flush when we use the Ryocap sheet method later, so might as well do it that way every time... Trim the mesh to fit the screen, that way you aren't dealing with more material than you need, and the OCD part of your brain won't be driving you crazy...

Now, we are going to need a crazy bright light source to expose our emulsion. Well, sunlight can be used, and is honestly ideal, but I prefer the control of an exact wattage bulb. That makes it a known factor (don't have to deal with clouds, angle of the sun, sunspot activity, UFO's blocking the sun, etc) and will allow you to tweak your exposure times. This is important. To get more or less detail, the exposure time is important. Again, there WILL BE A LEARNING CURVE. Luckily, this stuff is cheap, and we can afford to experiment. I grabbed a big clamp style light pot I use on jobsites when I do one of my other myriad side jobs. These clamp to a stud nicely and are great for this kind of thing. Ignore the sawdust please...

In this pot, I put a big 250 incan bulb. Now, let Obama and his incandescent light bulb killing cronies have a headache because I hooked this thing up... And yes, I am one of the people who has been hoarding incandescent light bulbs.

Now, it should go without saying, have a nice clean place to work. This stuff is easier to set up ahead of time, so do that now. And now that we have a nice bright place to expose our screen we are good to go. Sharp eyes will notice a big change in this little area of my shop later..

 

[Overmountain]

Alright, if you are using any of the bulk emulsions, like the Speedball emulsion, you will receive two bottles. One large one and one small one that holds the sensitizer. Follow the directions for these bottles and mix the emulsion. These things have a shelf life that is terribly short. Hence the discovery of the Ryocap sheets we will cover later... But for this stuff you can extend the shelf life by putting it in the refrigerator.

Again, mix the emulsion per the directions and set it aside. Now we need to wash out our screen before we stop. We need each little pore to be nice and clean and a little bit of moisture actually helps the emulsion bond to the mesh (or so I am told.) So, just throw it in the shop sink, or your kitchen sink, w/e and have at it. A light rinse is all that is necessary. This stuff is basically fishing line, so it will stand up to a nice heavy stream...

After rinsing the mesh, sling it dryish. It doesn't need to be bone dry, just not dripping wet. We can now lay it out for application of the emulsion. The screenprinting shops do this on a rack or a special table (at least JRM does) but just some newsprint and a good flat surface will work. Now, this is one of those things that has a technique that must be learned, so the first couple of screens might not be dead smooth. The screenprinting shops also lay out a border of masking tape for this stage to make a pretty little rectangle in the middle of the screen for use as an inkwell later. We don't need that so it is not a necessary step.

Now, we need a squeegee. I like the bondo squeegee's because they are cheap, easy to clean, and you can work them a bit to soften them. I have used bondo squeegee's for years, and learned with a little bit of working they can be softened and the edge can be worked against a jeans clad leg to give a bit smoother pull across materials.

Pour yourself a little emulsion on the screen in a nice straight line across one side of the screen... A little goes a long way. Let me repeat that... A little goes A LONG WAY with this stuff.

We want a nice thin coat, after all we are just trying to block the pores in the mesh, nothing more. Thick is great for those big blocky images the screenprint shops are going for most times, but for a small image we want it nice and thin. Spread it on with nice even strokes. It will push through to a degree, and when it does, flip the screen and squeegee it the opposite way. This stuff is light sensitive, so don't go crazy with the lights, but at this point it isn't as sensitive as it is when it's dry

Now, you should end up with a nice even coat on the screen. It should more or less look like this...

Now we need to put it in a nice dark place to dry. Keep a watch on it, we don't want it to dry and then sit for a long time as the emulsion will set up without light exposure if it just happens to sit for too long. Yes, I am setting it on my snare-drum for those that have sharp eyes and recognize the Remo pinstripe heads... Setting the frame up on some small blocks will help air to circulate and dry a little quicker.

Remember, a dark room...

Now, you can actually use a dark room bulb, or a special yellow bulb to use in the room where the screen is drying, but just keeping the light exposure to a minimum is plenty...

Ideally while the screen is drying is an ideal time to print off your patterns for the stencils. IMO you might as well put together as many designs as you can while leaving them reasonably spaced. Print your designs off on plain paper and double, triple, and quadruple check them for correctness. Remember that transparency sheet is expensive. The up side of using laserjet transparency material in an ink jet is that they can be wiped clean and used again. There are diminishing returns however as there is just a tiny bit of grit to these sheets, and it will hold a little ink here and there each time. I have found they get cloudy after a couple of uses. But, remember this whole project was born out of trying to stretch a buck... Here is what I will be exposing this time...

Also during the drying set up your sink/hose area for washout of the image. I use a big stainless sink with a spray hose and a toothbrush. Lukewarm water will be used in a nice moderate spray when we do wash out, so have this ready to go.

Now, after the screen has dried, and thoroughly for this step, it is time to expose our images. Using a piece of glass or two (very clean glass) to lay on top of the image can help keep it nice and firmly placed against the emulsion and give you a sharper image. If your image has very thin lines, it is possible to darken it up by printing two sets and laying them on top of each other. Now, that takes a bit of alignment help, and IMO is another area where the risks outweigh the gains. If it is off by even a hair, there will be a blurry line instead. It is better to just hone in your exposure times to get those nice crisp details. Place it under the nice bright light you set up earlier and let it ride. There are charts available here and there that will give you a rough idea of the time you will need for exposure.

Now, after exposure is a time sensitive little bit of running. You should have your washout area set up as advised previously. Immediately after removing your image and emulsion from the light, get it to the sink and start the washout process. A steady stream will wash away any unexposed parts of the emulsion. You can probably see the image in the emulsion at this point as a very light variation in color between the two differing emulsion exposures. Just scrub until the image is clear. Too much water will soften the emulsion and it can be scrubbed off the screen.

Here is another washout shot, in this one you can faintly see (well, it would be better if it wasn't as blurry but I am my own photographer) the image showing up. This is a very small screen I did for a single cursive 'Overmountain' logo.

Once done with the washout, it is drying time again... This time light exposure doesn't matter, and the image is pretty well set in the screen. It will dry to a crisp sheet on the frame. Now, screenprinters leave the screen intact on the frame as they will be dragging ink across the screen against the recipient surface. We won't be, so we can cut it free and cut out our individual images. I didn't take a pic of this process, sorry, but it is self-explanatory. Now, there are products available to wash out screens for re-use, and that is well and good if you goof a screen and want to use it again. But, for the most part, we are using such small amounts, and needing small stencils, so we can cut away... This is what you should have when you are done. You will notice that it is pretty darn crisp, but still not enough for my taste, so we will try the Ryocap sheets next...

Again, inconsistent picture taking here... This is an etch I did with a design that was supposed to look like an old printing press laid it down. Now, I will cover filling the pin holes in the screens later, but here I left them because I wanted that splattery look. This was done as a nameplate for my drill press... and just for photographic value... It was artificially patina'd steel as well etc...

Back shortly for the Ryocap...


-Eric

 

[Overmountain]

OK, So, like J said below, and I had discovered by talking to a couple of other people in the industry, the Speedball from Diazo is not the best stuff in the world. It is dirt cheap, but has a terribly short shelf life of a maximum of 4 months. And that is refigerated. I did my best to remove the air gap at the top of the bottle by sticking a few ball bearings down into the bottle, but I have my doubts that it will last that long. Better get to making those t-shirts fast!! Hah! I am thinking of doing a sign or something just for fun, but I digress...

I don't think I mentioned it before, but I am using a 315 mesh.

My biggest issue was that you have to kind of guess as to the amount of emulsion you need. Well, I did, as it isn't a skill I am practiced at. So you either have to remove some or add some as you squeegee it on... And it is very hard to get it dead even. Even on a small screen that fits your squeegee perfectly. And that is a big problem when you are talking about doing a stencil that is only an inch long. What if the thicker portion is on one side of the logo, and the thin on the other? If you use a bigger etching head like I do, it could cause it to sit at an angle, not applying enough pressure to parts of the logo.

Given these concerns, I spoke with my friend and he recommended I look at the Ryocap emulsion sheets which are available here. And before anyone can have that thought, I do not work for or get royalties from this company, it is simply where I found the sheets that I am using... They are so much easier to use it almost makes you want to kick yourself (or your friend) for not using them in the first place... They are 10"x15" which is more than enough material to get quite a few stencils out of. Especially when you are able to cut it to the exact size you need...

Ryocap sheets are a pre-sensitized emulsion sheet on a plastic sheet. They will arrive in a dark black package several layers thick of 18 mil or so plastic. Don't just go tearing into that willy nilly, it is there to keep the sheet from being exposed. I had read the reviews, and there were statements about adhesion to the screen issues and the like, however I was told by my friends in the business that they adhere just fine, it simply is a technique problem if they do not... Well, they were right and wrong, and we will get to that in a minute. The best part was the encouragement that it was much easier to get it on the screen uniform and thin, and would result in much clearer results with more detail... This stuff also has a much much shorter exposure time and works better with just a bright bulb and doesn't need as much UV specifically.

First, here is a piece of the Ryocap sheet. I figured I would go ahead and waste a small portion just to demonstrate what this product is, and how it is set up.

Pretty plain and simple. It has a rather stiff plastic backing that can be separated just like window tint from its backer if anyone is familiar with that process.

The best part about that is the ability to apply it directly to the steel... I tried with the speedball stuff, however its consistency made it nearly impossible to get it on in the right thickness for what I wanted, and did not like to stick to the steel. This stuff is uniformly thick to start with, and is very very sticky. I should mention at this point, have extremely dry hands, or wear nitrile gloves. Any little bit of moisture makes this stuff start to get sticky. Here, I just used a shop cloth to dampen the surface of this 416SS drop. Then it is just a matter of laying the emulsion sheet directly onto the steel. From there it can be left to dry, exposed, rinsed, and etched. I wish I had an etched example, but I am going to need to do it on D2, stainless, or something. On plain carbon steel it develops little rust spots under the emulsion which result in little pinholes because the emulsion washes away from those same as it does the exposure.

Ok, this is the neat part of this stuff as well. You don't have to build a frame if you don't want to. I have done it both ways, and while building a frame allows for a smoother placement of the emulsion on the mesh, it isn't a complete necessity.

Same as before, either build a frame and place your mesh on it or just cut your mesh to size. It is again going to have to be washed, and this time it can stay wet after the rinse. I have started using just a drop of soap as I wash the screen as JRM recommended it, but don't know if I can tell a difference from not using soap. They have done way more of this stuff than I have, so if they recommend it, I might as well do it. When the screen is left wet, however, it needs to be with clear water. I use distilled water for everything in the shop. We have hard water here, and it will leave spots on almost everything. I figure if it is carrying that much calcium and such in each little drop, I certainly don't need it on or in anything I am doing in the shop. Plus distilled water is pretty cheap.

Cut out the size of emulsion that you need. Lay that out on some clean flat surface. These pictures are where the keen eyed among you will notice a difference. I will elaborate in a minute.. I will also apologize here for the blurry pics. I had to do all of these in low light since this stuff is sensitive to light at all stages.

Here is the mesh on a frame, and just cut to rough size. In the rough cut piece, it is already laid on top of the emulsion sheet.

If you do build a frame, (and I do recommend it as it just makes everything a little easier), take a little distilled water and squeegee it into the mesh to the point where every little hole is holding a little water. In other words, wet, but not dripping.

Then lay it on the emulsion sheet. You will see it contact the surface and see the emulsion as it does.

If just layed on top of the emulsion sheet add a little water to the top and start squeegeeing into the mesh. The mesh will start to be see-through.

If out of a frame, I then trim the mesh to a bit more manageable size.

Ok, the process from this point on is pretty much the same. You want to start squeegeeing the mesh onto the emulsion.

The adhesion problems seem to be a failure to properly squeegee everything together. I had issues the first couple of time, and you will see some missing parts of the emulsion in some of my pics in a few, but noticed this start to go away as I got better at my technique. You should start to see the emulsion coming through the mesh. Add a couple of drops of water as you go about squeegeeing the mesh and is dries out. Once you are pushing a good bit of pink around, the emulsion is pretty well adhered.

After the emulsion is thoroughly on the mesh, you can place it somewhere to dry. The sheet that is not in a frame has to be hung up obviously, but the frame can be set aside like before.. You can remove the plastic backer at this point, or when it is dry. It will tend to take a little of the emulsion with it when it is still wet, but it speeds up the drying to have it gone. I wasn't in a hurry with the one in a frame, so I left it on, but for the one out of a frame here I was short on time so I took it off. You can see a couple of places where it took emulsion with it. This can be blamed on my technique as I didn't get it into the mesh enough. Later attempts were a bit better.... None the less, it will work fine for our purposes.

Here is the logo I am doing on this sheet. Placing a paper towel between the transparencies and making sure I don't slide them has so far allowed me to hang on to these sheets for later use. As an alternative, one could always use a heavy black paint that is a good light blocking paint and paint a logo or design on clear plastic to transfer it to the emulsion.

After the emulsion is dry on the mesh, same as before, time to expose it. Lay the transparency down on the emulsion, place a piece of glass or heavy plexi on top to help hold it as flat to the surface of the emulsion as possible. I used the same setup as before, the work light with a 250W bulb. In this instance it only took a couple of minutes of exposure instead of the 45 minutes the Speedball took. The light was also able to be placed a little farther away, which helped keep everything nice and cool. You can see a little stretching in the mesh that was not on a frame. Another reason I recommend using one.

Once again, after it is exposed, rinse the unexposed emulsion from the sheet in the same manner as before. This does need to be done quickly, not 1095 quenching territory, but don't dilly dally. I discovered the Ryocap also washes out a lot easier than the Speedball. Again, as J pointed out, there are much better products out there obviously. While washing, you can hold the design up to the light to see that everything is coming out as it should.

After everything is washed clean, you can set the mesh out in the sun to let it dry and also set the emulsion just a bit more. If it is raining, pop it back under the bulb you used for exposing the design... After everything is nice and dry, you can inspect your results. Here, you will see how mine turned out and notice that there were a few spots where the emulsion didn't adhere to the screen. If we were doing a t-shirt, this would have been a no go. For something as small as a logo to be etched, it isn't that big of a deal... Keep in mind here also, this is a pretty small logo...

At this point, I pick out the keepers from the throw aways and cut them out. Remember to leave enough space around the logo to put down some vinyl tape. I hold them up to the light and look for pin holes...

They make products for the screenprinting industry to fill pin holes. If you want to go that route, I am sure they work well. Instead, I just stole a bottle of HRH's (Her Royal Highness) fingernail polish and dabbed the holes. This has seemed to fill them as well as anything else...

OK, this is where we are at for the moment. The transformer went out on my etcher and it is currently disassembled. As soon as Friday gets here, I will throw this etch on a piece of steel and get a couple of pics. It should do well. This looks much clearer than the Speedball ever did, and using a little acrylic paint to put down a little test blot, it looks nice and clean. Still not approaching the professional stencils or photoreactive stencil material IMHO, but much better than trying to cut a design out of a piece of vinyl tape with an x-acto knife or scratch the design in a blob of fingernail polish. Again, I am hoping this can get refined to the point where it is a viably cheap method of doing some one off etching or etching for someone on a budget. I had seen a maker who has transitioned into doing only FeCl etching on his logos and such. It looked incredibly clear, and I was wanting this to work for that, however it doesn't. Like almost all other stencils, this one will allow the FeCl to run under the stencil which ends up etching everything inside of the tape lines. I think for doing that, I am finally going to have to break down and go back to the sign shop for a few sheets of die-cut vinyl logos. That was the route I went for a few projects where the customer requested some type of personalization or marking, and the clarity there is really hard to beat...

Well, that is where this all stands. To those of you who do a lot of screen printing **J, talking to you here bud** chime in and direct me to as good a result as we can get with this stuff... I am convinced that this is a viable option, and that it could possibly be nearly as good as the professionally offered stencils. Speaking of that; does anyone know what process is used for making the professional stencils like TUS Tech makes? I would love to learn the process for making the stencils that last for several hundred etchings. I believe Ernie uses photo-reactive film, which is really good stuff but only seems to make it through a couple hundred etchings. Which isn't bad or anything, but several thousand etchings would be even better. If someone can point me in the direction of that process, I will see if I can make it a viable at home option for us and post up a how to on that...

Cheers. Thanks for bearing with me on this.

-E

 

[jwesthurl]

A quick word about emulsions...Speedball Diazo will work fine for making these screens, especially because it is probably going to be the most readily available for most people. The problems with Speedball Diazo are very short shelf life and exposure times. Once you open the emulsion it should be refrigerated. It will last a MAXIMUM of 4 months in the fridge. Depending on screen size and bulb wattage, exposure times can be extremely long...45 mins to 1.5 hours. If you think you will continue to use the emulsion over time or have a need for larger quantities, a more professional emulsion might be better. I personally use Ulano products which are pre-sensitized and have a much longer shelf life at room temperature for a decent price. Ulano QTX has very fast exposure times and is good for low UV lamps. Another quick tip...after exposing and washing out your screen, place it in the sun to further harden your emulsion and to be sure the emulsion is completely exposed.

 

[Overmountain]

This is where I like the Ryonet Ryocap sheets. Like J stated, the speedball is rather sucky for what it is. I think J mentioned this the first time I started looking into these emulsions. Hence why I got the Ryocap after being shown this stuff by JRM. It has a nearly infinite shelf life as long as it is protected from light, has no sensitizer to mix, and can be used in preset quantities by just clipping bits off the sheet... Pretty ideal for what this is... Like the Ulano, it also exposes very quickly under a low UV bulb, and sets up very hard in the sun.. And thanks for adding the bit about drying in the sun after washout. I meant to add that. It really does result in a near plastic product when finished. J, please add some technique to my fumblings. I have screenprinted a total of one t-shirt at this point, and that was under close supervision at JRM. Hopefully you and some of the others here with a lot of screenprinting experience can refine this a bit and help me turn it into a really workable solution for the one off and small batch stuff we tend to do a lot of.

-Eric

 

[Overmountain]

Shew... Finished... Mostly..........

Sorry guys, I don't normally do these How To's. I will try to do a little better on the next one.

-Eric

 

[Salolan]

Thank you Eric for this, it is appreciated. Yet another example that we almost literally have to know something about everything just to make a knife!

Oh, and that's a good looking work bench!

Chris

 

[Overmountain]

Thank you... That was the sharp eyes part!

In part one it was bare wood... part two I had my granite!

I have the free use of a Bridgeport Series 1, but I have to drive 20miles to get there. I drive lifted quad cab F-250 'stroke... Diesel ain't exactly cheap. So, I managed to convince myself and HRH that I needed a little mill/drill or something as 80% of what I do could be done on one and done in the time it takes me to drive up there. So, after a lot of looking at worn out equipment, and a bunch of other crap, I decided to pick up one of the HF jobs. For all of people's griping, it really is a nice machine. Clean up the cosmoline, lap it a bit, tighten this and loosen that and it runs like a champ. So, I needed a table for it has been taking up real estate on my workbench that I need badly for mowing season.

So, after over building this table, I decided it would be nice to have a big hunk of granite to work on. Basically a surface plate that can be worked on. Granite is dead flat and cleans up nicely.... So I made a visit to Design by Nature here locally. They do nothing but granite. I told them I needed a 2'x2' piece as thick as they had. She asked if it was for a vanity. I told her a workbench top and I'd take the ugliest stuff they had. She instead offered up anything I wanted from their bone yard and even offered to cut it... So I wound up with this piece of choice stuff and an 8"x8" 3/4" thick piece for sanding and such. As well as an offer for anything else I needed if i wanted to cover other surfaces. Man, the generosity of some people actually gives me faith in humanity sometimes.

So here that is finished out with my constant shop companion... (except she goes elsewhere when I'm using chemicals, grinding, or sanding.) Have to consider her lungs too...

And yes, I have discovered that knifemaking calls on almost everything I've learned about working materials and such, as well as requiring us to constantly learn new little things as we go...

So, sorry for bombing my own thread here... lol.

-Eric

 

[jwesthurl]

A couple of things I can think of off the top of my head...
really dialing in your exposure times may give you crisper stencils, scrub as little as possible, higher pressure (like from a shower head) should do the trick without scrubbing - avoid high pressure to the back of the screen, use cool water.
When you are exposing your screen, use a dark, matte material under the screen. It helps you avoid bounce which can expose your screen from underneath and make your stencil difficult to wash out.
I think capillary film is a good way to go because it's uniform but you can get even, thin results with emulsion.

I got poor results from my stencil but I also don't have an etcher. I was using a pad hooked to a battery charger. the water just finds it's way under the stencil and washes it out.

Here is a pic of my stencil...it's about 11/16ths long. You can get pretty detailed with emulsion. By the way this is Ulano QTX on, wait for it...Chiffon fabric from the fabric store! Exposure time 7 minutes with a 150W incandescent bulb at 12 inches from the screen.

You did a fantastic job on the WIP. I think if you can figure out the optimal set up on your etcher it should work great. Hope I helped a little!

 

[Overmountain]

That looks awesome J. That's funny because I honestly considered chiffon fabric; and that may help. I have to press pretty hard with my etcher. I think a thinner fabric might be the key to lighter pressing. The ulano stuff looks so crisp. That is my next try. The capillary film is great for the novice that I am, but I can see how a thinner hand laid emulsion with a quality product can make a difference. I think JRM uses Ulano. Basically because the emulsion color looks like yours. But my first convo with him he said 'emulsion' but was not specific. Diazo Speedball was honestly the first thing I found. Guess I should have caught your attention sooner

A real etcher makes a big difference. Dialing in an etcher will make the wet areas under the stencil not a big concern. The current takes the path of least resistance and as long as there isn't enough current flow to overload the circuit made by the etching solution through the open parts of the stencil, it tends to not under run. At least that's my take on it... It has been 20 years since I studied electrical theory to any degree... But, like the overmountain logo up there, I think it looks pretty darn good for a workshop done hack...

I'm shooting for my first entry into the stickies here, so truly appreciate all the help I can get. Lol. I'll consider it co-authored honestly as you are truly the expert here... And thank you for your help and complimentary remarks.

Keep it coming...

-Eric

 

[jwesthurl]

As you can see, you can get decent detail on the chiffon fabric. Chiffon is not a bad choice for these stencils because you are just cutting it up after they are done. If you were going to screen print t-shirts, I would definitely use screen printing mesh. The Chiffon will not hold the tension needed for repeated printing.
Thanks for the compliments but I'm no expert, I've just done this enough to kind of know what I'm talking about, lol.
I do have one other idea that I might try tonight...I'll keep you updated.
Josh

 

[flatblackcapo]

Thank you Eric for taking the time to put this together. I have learned a lot!

 

[jwesthurl]

Just a quick update on my experience...I remade my stencil using a slightly thicker application of emulsion. To etch, I used a battery charger, piece of felt and salt water.
This is an absolutely workable solution, especially if you already have the materials handy.
Here are the results on my latest knife.

 

[Stacy E. Apelt - Bladesmith]

Nice deep etch.

A few tips:
Placement is poor. The mark is in the middle of the blade. It would be far better placed just below the spine near the ricasso.
While not to big, it is a bit larger than most. This is partly due to the stencil making method I would guess.
The etch is only an etch at this point. The mark is made by using AC voltage after the DC etch. On most etcher systems this is done by flipping a switch to bypass the bridge rectifier. This will make the etch turn darker.

 

[jwesthurl]

Thanks for the tips Stacy. The size of the mark is sort of arbitrary. That's just the size I printed, and although I have printed smaller I haven't tested the limits on size yet. And sadly, I don't have a means of marking yet. Maybe soon.

 

[Stacy E. Apelt - Bladesmith]

If the battery charger is one for a car, just wire in a SPDT by-pass witch that takes the bridge rectifier out of the circuit. That will deliver 12VAC instead of 12VDC.
If it is a modular plug-in type, like from a computer power supply, you can't do anything to it.

 

[jwesthurl]

It is a car battery charger. Can you provide any further instructions on how to wire the switch? I would like to try it.

 

[Overmountain]

Very nice J.
Mine are getting there so I'm still tinkering... Used chiffon and some fake silk product.

I have decided to go in with a friend and order a bulk amount of industrial photoresist film on a substrate that is microscopic. I am told it is used in the industrial world for thousands of markings that are done very quickly. The price works out to about $0.75 per square foot. For that, I can't beat it for my purposes. If this is good quality stuff, I will pass out some samples to you guys for trial... Then possibly sell small quatities of it for a reasonable price. I am anxious to see what substrate they are on...

With a friend who is a little more electrically inclined (I know my electrical stuff as I was a MECP installer for audio and car alarms, but he puts me to shame...) and build a really nice etching machine/power supply. Honestly only if we see an interest though... It will be AC/DC obviously and have voltage adjustment from 0-36v. It will have a constant on, as well as a momentary that can be a foot pedal or hand held if desired. It will have a volt meter and possibly an amperage display though I don't see that as very important... We will incorporate a timer in the future, but this first one is 100% manual. I have toyed with putting in a PWM for both DC and AC. If anyone can see that as important I will do so with two DPDT switches to run through.
It will also have a hand piece with felt and a graphite electrode. The hand piece will be attached via gator clip so the leads can be used for plating or anodizing baths. Or they can be used to power whatever falls into the voltage range.

I am determined to keep the price reasonable too. I don't understand why markup is so high on these machines. I will be honest, we have about $120 in the materials. Our labor isn't worth Bill Gates type money... lol.

I have also seen some newer etchers that use circuitry with wierd frequency tinkering, timing, etc lately. I'm not trying to slam them... but that's kind of like using a back-hoe to dig a window-box flower bed. When current flows, metal particles move. Etching and plating are very simple processes fundamentally speaking. I know there are oddities for some metals but for the most part it is insanely simple. I have seen an etched logo done with a home built transformer and rectifier setup (like my current etching machine) and the same marking done with Electro-chem's top of the line machine. Done with a professional stencil you can't tell the difference. Voltage control is nice and fairly important, but aside from that maybe a timer for repeatability sake, but that can be done easily with a pot-controlled delayed off relay.


Just my $.02 and I'm sure I offended some people, and maybe someone can explain and show me why the price mark-up is as much as it is, and how the computer run etching machines do whatever they do. I welcome the info. I am delving into the etching thing as deeply as I am recently basically from curiosity and good old tinkering.


Wow, bombed my own thread. Cool. Too much caffeine.

-Eric

 

[jwesthurl]

thanks Eric. I'd definitely be interested in trying the film. Keep us updated

 

[Overmountain]

Ok. So, I have found a cheap source for the negative acting (what we want for stencils) photopolymer film used in the PCB etching industry. We want negative acting, as the converse wastes ink trying to make a transparency. This stuff can be used on a very thin substrate or directly on the knife. Directly applied to the steel it makes for a very clean image as you will see below.

So, this is the film. Simple stuff, a sheet of photopolymer between two sheets of clear film. This stuff is thinner than thin...

For this demo I am just using a piece of hardened 4130, unidirectional finish at about 600 grit.

The film, as stated before, is trapped between two clear film layers. To apply the film to a surface we need to remove the clear film from one side. I use the old tint installer trick of taking a piece of masking tape and applying it to both sides of the film. Then pulling in opposing directions. This may begin to remove the clear from both sides, and if it does just use a finger to direct only one side to release.

Then simply apply the uncovered side of the film to the workpiece. The good thing about this stuff is that it can be worked with under any light that doesn't bear heavy UV. I have used it under CFL lighting and not had any issues.

This is the image I am using for this etch. I wanted to really push this stuff so I chose a cursive logo, about 6pt font, with very light details.

We then want to expose the film with the positive logo on top, just like before. For this stuff, same is true, place a piece of glass on top to get it all as flat as possible. Any light bearing good UV output will work, the sun is a great one... Or, I have since found the best (quickest) results using a dedicated UV source... Any very bright LED if is in the blue end of the light spectrum will work, but a black light is better. Even better than that is a UV light in the nearly non-visible spectrum. I have a 400nm light that works very well...

After the exposure, you will be able to see where the film has changed slightly. Now remove the other layer of clear film from the photopolymer from the mask.

With the film you need both a developer and a remover. The developer can either be a premixed type in a bottle, or dry that is mixed with water. I chose dry, as you can mix as needed. It mixes in my case at a 100:1 ratio water to powder. And as always, I use distilled water to avoid contaminants.

Then dunk the whole shebang into the developer.

After the developer, dry the mask. Then dunk in the remover, and same thing, wipe away (a light touch but a little scrubbing is necessary to remove the non-exposed film). You will be left with a perfect mask for your etch.

Then just fire up your etcher and etch away. This type of mask holds up very well to higher voltages if your unit happens to be built off a 24v transformer or the like. I have tried an etch with just an old phone charger, all the way up to my etching machine. So far this masking technique works well with them all. In this example, I did two etching cycles of about 15 seconds each, and one mark for about 10 seconds.

Then just wipe away the mask with some acetone.

After a brief wipe down with acetone, and a brush with 0000 steel wool, this is what you are left with. Pencil for scale.

This gives you a good idea of the depth of the image.

And an idea of how it compares to the original...

So far, for one offs this is the best outcome. Nothing will top the professional stencils for multiple etchings, but for a one off on a piece, this seems hard to beat. The price would break down to absolute pennies for this method. I do the same logo for my maker logo on almost everything, but have been looking for something like this as I would like to put the 'Overmountain' brand on things from time to time, and want the font to fit the rest of the design. This means either ordering a sheet of pro stencils with many fonts, or using something like this.

I have a very thin plastic based mesh substrate (micron level filter media) that I got from a friend. I am trying to see how well this stuff sticks to the media, and how many etchings I can subsequently get out of that.

The film, plus developer and remover is sold in kit format for etching PCB's on several different sites, as well as eBay. The price is fairly low even in those places, but the best price breakdown comes from buying this stuff in bulk. I think my roll here is about 3'x100', and the developer and remover chemicals are about 2 pounds each in plastic laboratory type bottles... I am yet to see how long the mixed up developer and remover I have will last on the shelf and after multiple uses... I will also see about parting with some of this stuff, and for what price in the near future if there is much of an interest. Until then, if you want to give this a try, the stuff is available by simply searching for 'PCB etching film,' or 'photopolymer film,' or simply 'photoresist film.'

-Eric