Stabilizing Wood: Physics, Chemistry, Materials, Techniques, and Performance: "Just the facts Man"

[Cushing H.]

Lacking definitive input from the moderators, I am going to follow Randyb's request and start a new thread on this topic. To try to avoid (now and in the future) heated arguments based mostly on opinion, I am proposing, and requesting, that contents of this thread be restricted to concrete knowledge of the underlying mechanisms, materials used (or processed), processes used (with reasonable detail in terms of time/temperature/pressure, etc), and results. I can supply a great deal of the background knowledge and "theory", and am hoping/planning that I can perform and read out to you some specific experiments with regard to resin penetration, AND performance of the resulting impregnated wood (especially moisture uptake and dimensional stability. I wish I could do some measures of mechanical strength, but do not have the resources for that... ).

There is also a great deal of fact-based experience out there - some of which has already been related on the recent previous thread ( https://www.bladeforums.com/threads/stabilized-wood-source.1672650/ ) - especially those by Ben at Greenberg, Willie71. I would like to see those comments re-posted here if the posters agree. I am sure there is other experience/data-based information out there that others can contribute.

I would like to re-iterate that I have no argument that the K&G process results in better penetration than anything we can do at home (and I can/will tell you just why that is). What remains unclear to me is: under what use-conditions does that penetration difference result in a performance difference? (and if so, how great is that performance difference). I have spoken with the folks at K&G (great people!) - and while they have measured penetration, they have no data on the question I am asking - hence my attempt to start this thread and effort at data collection/generation myself. (the folks at K&G know what I am trying, and are ok with it....).

PLEASE speak now and let me know if you are interested in my pursuing this effort. If this is just me and no one else is interested, I will stop. But if there is interest in understanding how your stabilization "home processes" can be improved, and understanding more concretely what their reasonable limits are - then I think this will be useful for folks now and in the future.

(I am sure some are asking "just who is this new guy to do this"? I resist throwing my credentials out there (all of your extensive experience in the craft counts far more than those). suffice it to say that my education and career experience are highly aligned with this particular issue of stabilization and the materials involved. I hope that I can use that to educate (a little), and to help put clarity to this question of "what is good enough versus use expectations" when it comes to the use of stabilized materials.

Please let me know your thoughts...

 

[samuraistuart]

Nothing to add, but I'm interested. I have never attempted home stabilization simply due to what I've heard in the past, "It's not good enough". But, like you, I am sort of left with "how good is good enough?" I rarely have an issue with unstabilized wood, but I did just recently have to redo my sister's chef's knife handle due to the highly highly figured walnut curling up at the front. She didn't even notice it until I was out her house the other day. This made me think if I should be attempting at least something to stabilize the wood, rather than just the oil rubbed finish. I'm interested to hear opinions and experience.

Edit to add: I missed your other post. Great info. I was going to give the particulars of what I did correctly, or not, but that isn't in the purview of this thread.

 

[Ken H>]

I have no argument that the K&G process results in better penetration than anything we can do at home (and I can/will tell you just why that is). What remains unclear to me is: under what use-conditions does that penetration difference result in a performance difference? (and if so, how great is that performance difference).

Opinion: Penetration shouldn't that hard to measure - cut block in half and see if the resin is all the way thru. Wood does NEED to be 100% penetration because the portion that doesn't have resin penetration isn't stabilized and will show up in finish. If the wood needed stabilizing, then anything less than 100% penetration is a failure.

"IF" (and this is a BIG "IF") the resin is equal, then home stabilized wood that has 100% penetration "should" be fairly equal to K&G. I use K&G to refer to WSSI, K&G, and any other truly commercial operation of equal reputation.

More Opinion: The biggest difference between home stabilized wood and K&G is penetration. With home stabilization an open pore wood will take up resin nicely and provide 100% penetration. A dense small pore wood (Black Walnut and similar woods) just don't work very well (little penetration) at all with home stabilization. K&G gets great results. I understand they can even get rosewood to take resin. Maybe that's Rosewood burl that might be more open pore than solid Rosewood heart that sinks in water without being stabilized. My feeling (and what I've read on other sites (Ben's, etc) is a natural wood that's dense enough to sink in water doesn't really benefit from stabilizing.

Anything less than a good 2 part resin (Cactus Juice, etc) isn't truly stabilizing. Anything less than pulling under vacuum to 29" Hg (hand brake bleeder pump, etc) for required time isn't truly stabilizing. If the finished block doesn't sink or float even with water same as K&G blocks do, it's not stabilized correctly. Minwax wood hardener is NOT true stabilization. Pentacryl method is NOT stabilization.

I think this horse has been beat pretty much to death! Most of us have minds that are already made up and have written our opinions.

 

[Greenberg Woods]

Lets see what I can get down. First things first, here is what I said on the other post.

I see quite a bit of misunderstanding whenever the difference between home stabilized and professional stabilized wood comes up.

I've had about 3500 pounds of wood stabilized by K&G, I've talked to brad about his process at great length, I have my B.S in chemistry, and my exit thesis was about wood stabilizing and adhesives.

3 things set professional and home stabilizing apart.

Equipment, materials and expertise.

Equipment: people always talk about the importance of a low vacuum or of long soak times as explanations for why their home stabilizing set ups are just as good as K&G. The issue is, vacuum is a diminishing return. The benefits of lower vacuum become exponentially less intense as the pressure lowers. That is where k&g is diff rent them any home set up. They use a pressure cycle. The do a vacuum cycle followed by a high pressure cycle to get better penetration.

Materials: K&G's resin and cactus juice are the chemical. Kind of... the resin being used is Methyl methacrate. It's basically the monomer that makes up acrylic. But the grade of the chemical used varies. Cactus juice is a relatively low grade. It contains a variety of side products, partially pulverized monomer, and other byproducts that lower the penetration and curing potential ofnthe resin. K&G use a much higher grade, and it is EXPENSIVE. That's just a fact. It's expensive stuff. Good chemicals are.

Expertise: brad had been doing this a LONG time. He knows what he is doing, knows how to tweak his processes, they check the moisture level of.each and every block.

The results: K&G stabilized wood is better than home stabilized wood. I know someone will comment that I havnt tried THEIR stabilized wood and I dont know. I have handled thousands and thousands of pounds of stabilized wood. I've also handled lots of wood stabilized in home set ups. And I can instantly tell the difference. The weight alone is a give away, in medium weight woods like hard maple, mango or tamarind K&G wood is generally 20-30% denser. There is also the matter of consistancy. In those thousands of pounds of wood, I have had maybe 10 blocks with sticky patches inside of uncured resin. My shopmate has a failure rate of roughly 1 in 10 from blocks purchased from home stabilizing.

Can home stabilizing work? Yes definitely.

Are home stabilized woods often good enough for use on a knife? Yes definitely.

Are they on par with K&G? No. Full stop.

Now to address the question. What is good enough?

I have no idea. That depends on who you are, what you need and what you want. My shopmate has a variety of home stabilized woods that he uses. They are heavier than the natural woods, but significantly less dense than the same species having been stabilized by K&G. I can distinguish them blindfolded without difficulty.

But do those home pieces work for knife handles?

Yes.

I have been talking about and defending K&G stabilized woods for many years now, but if you read my posts and my comments, I will never say home stabilizing doesn't work. It does work, it puts a resin inside the wood which will add weight, make the block more resistant to warping and aid in finishing.

But it wont be to the same degree as wood stabilized by K&G. That is the point. I have no issues with people using or selling home stabilized wood, but I think people should specify, because it is objectively a different process that yields different results of quality. I sell high end material. I do not stock any lightly figured maple or whatever, When i stabilize wood it is because that wood has a high density of figure and will make an excellent handle, and I find that my clientele want the top quality wood and they want the best stabilizing, and that is what I use.


I should also probably mention what stabilizing does and does not do, since there is some confusion about that.

What stabilizing does do:

It adds weight. This is useful both for balancing a knife, but also aesthetically. Heavy wood feels more solid, it feels more premium which makers and customers both like. This is very useful for some of the very light weight woods like redwood burl, sugi cedar, big leaf maple and other woods that are naturally very light

It limits warpage. This is one people seem to forget, but it literally makes the wood more stable. Wood will normally twist, curl and peel as changes in moisture cause different areas of the wood to swell. By impregnating the fibers with a dimensionally stable resin, a lot of this movement can be prevented.

It increases hardness: A lot of very soft wood like sugi cedar, redwood and box elder are simply too soft to use as handles normally. They dent with a finger nail being applied, and while they have beautiful grains would simply become too marred to quickly to be used in a knife. Stabilizing makes these woods hard enough to use without worry.

It improves finishing. Some woods have very open pores and do not finish to a glossy smooth shine. Woods like oak burl, walnut burl and spalted woods come to mind. By impregnating the wood with resin you are able to vastly improve the finishing qualities of the wood and get a really top notch finish on nearly any wood.

What stabilizing does not do:

It does not fill gaps. This is something I see all the time, and its wrong. Stabilizing will not fill checks, gaps or cracks. Stabilizing resin will only impregnate wood, and will not fill these gaps. These gaps can be filled with super glue or epoxy, but stabilizing will NOT do it.

It does not make wood waterproof. While the wood will become water resistant and wont warp with moisture, it WILL still soak up water. Dont think you can leave a stabilized block in a pool of water with no changes.

 

[Greenberg Woods]

Opinion: Penetration shouldn't that hard to measure - cut block in half and see if the resin is all the way thru. Wood does NEED to be 100% penetration because the portion that doesn't have resin penetration isn't stabilized and will show up in finish. If the wood needed stabilizing, then anything less than 100% penetration is a failure.

"IF" (and this is a BIG "IF") the resin is equal, then home stabilized wood that has 100% penetration "should" be fairly equal to K&G. I use K&G to refer to WSSI, K&G, and any other truly commercial operation of equal reputation.

More Opinion: The biggest difference between home stabilized wood and K&G is penetration. With home stabilization an open pore wood will take up resin nicely and provide 100% penetration. A dense small pore wood (Black Walnut and similar woods) just don't work very well (little penetration) at all with home stabilization. K&G gets great results. I understand they can even get rosewood to take resin. Maybe that's Rosewood burl that might be more open pore than solid Rosewood heart that sinks in water without being stabilized. My feeling (and what I've read on other sites (Ben's, etc) is a natural wood that's dense enough to sink in water doesn't really benefit from stabilizing.

Anything less than a good 2 part resin (Cactus Juice, etc) isn't truly stabilizing. Anything less than pulling under vacuum to 29" Hg (hand brake bleeder pump, etc) for required time isn't truly stabilizing. If the finished block doesn't sink or float even with water same as K&G blocks do, it's not stabilized correctly. Minwax wood hardener is NOT true stabilization. Pentacryl method is NOT stabilization.

I think this horse has been beat pretty much to death! Most of us have minds that are already made up and have written our opinions.

Penetration isnt as easy to measure as you may think. What if the outside is at 95% saturation, but in a home stabilized piece the very center is only at 60% saturation with a smooth gradient from edge to center.

 

[Cushing H.]

BUT “penetration” is not only about getting resin to the center if the block - it is about filling the pore space (both large pores and small). You can get resin to the middle of the block but still not get all pores filled. Agreed, minwax and pentacryl are not stabilization. I am talking about variation within the acrylic resin based technologies ONLY - still lots of room for variation and confusion with them.

 

[Tom Lewis]

I spent a lot of money to buy a vacuum pump, pressure tank, etc. I used a Loctite product called Resinol 90C as stabilizing juice.
I sent a block of wood to K&G and stabilized a block of wood that was the same size and weight. The block that came back from K&G was heavier than the one I stabilized. This was several years ago and I don't remember how much heaver it was, but I decided it was better for me to have K&G do the stabilizing.
If you do a search, you can probable find old posts that described my stabilization process.

 

[Cushing H.]

The block that came back from K&G was heavier than the one I stabilized. T

But ... HOW do you know (versus just believe) that heavier translates into “better” for your particular needs and use conditions? That is a jump being made here by many with no data, at least as far as i have been able to find... Again - "how good is good enough"?

 

[Cushing H.]

I think this horse has been beat pretty much to death! Most of us have minds that are already made up and have written our opinions.

Part of the point I have been trying to make is that, as a new participant in this forum - the resulting mishmash of opinions and statements is extremely confusing, and in fact (as you point out) - a great many do not understand what "stabilizing wood" really is and what it is doing (and how it is doing it). What I am proposing here is that this thread create (for me, and other new members in the future, and for those existing members who may not have truly and fully made up their minds ) a single place that tries to cut through that clutter enough that individuals can make up their mind in the future based on their particular needs. (Edit: and also to help them, if they choose to do their own stabilizing, better understand how not to screw it up... )

In a very similar way to what I tried to do regarding handle adhesion, I can bring to bear a lot of background information (and also add some new data - and I mean numbers and graphs) that will help inform those decisions....

 

[daizee]

Waiting (im)patiently!

 

[Cushing H.]

Lets see what I can get down.... lots of stuff... Dont think you can leave a stabilized block in a pool of water with no changes.

Thank you Ben (for the repeat, and additional information)! From what I understand I agree with everything you said.

 

[Ken H>]

Please allow me to state again, if I'm ordering wood it better be stabilized by K&G, WSSI, etc. If "home stabilized" it should be cheap enough for me to take a chance - if I order at all.

Ben, I agree with 99.9% of everything you said, and the .1% I don't have the knowledge to know if I agree or disagree.

On measuring penetration I cut the block open, look at the pores (cells?) under microscope to see the resin filled. Also, with a soft wood (or heavy spalted) like Ben mentions it's easy to tell if the wood is filled with resin or not. If filled with resin to the point of not being able to tell difference between inside and outside, then it should be good.

Heavier or not? - take two blocks of same name wood that weight the same per cubic inch (same density) before stabilizing, then weight after stabilizing. The heavier (more dense) block post stabilizing will contain more resin, and should be better. Take two blocks of stabilized wood and float in water - if they both float just even with water, or both sink, they're both about the same "weight/cu in" which is what we're really talking about - the density of the finished wood.

My question (as I stated above) is are the two resins equal? "ONLY" if the resin is equal does the two blocks have a chance of being equal and that is "IF" they both have 100% penetration. Take two blocks of spalted Maple of the same size, and both weighing the same so they can be shown to have same density. Send one block to K&K, and do a proper home stabilization with Cactus Juice. Clean both blocks up post stabilization. Weight both blocks - if they weigh the same they should be fairly equal ONLY "IF" the resins are equal. If you knowledgeable folks (Ben, I know his background and he's about as knowledgeable as it goes with stabilizing process) say the resin used in Cactus Juice is a relatively low grade and not equal to K&G's resin, then case closed as far as I'm concerned. K&G is better. Note, "different" does not necessarily mean "better".

Let's face it, knives have used wood like Black Walnut, hickory, etc for many years with success. Stabilization allows the use of woods that are beautiful, but wouldn't normally be suitable for handles.

One other comment, from my meager experience it's almost as expensive to use Cactus Juice and stabilize wood as it is to send to K&G. Perhaps if ordering by the 55 gal drum the cost could be competitive, but buying by the 1/2 gal you don't get many blocks from that.

Ken H>

 

[Cushing H.]

Weight both blocks - if they weigh the same they should be fairly equal ONLY "IF" the resins are equal. If you knowledgeable folks (Ben, I know his background and he's about as knowledgeable as it goes with stabilizing process) say the resin used in Cactus Juice is a relatively low grade and not equal to K&G's resin, then case closed as far as I'm concerned

All cured acrylic resins (if unfilled) have a specific gravity of around 1.2 (water is by definition 1.0) (ignoring temperature)... there is some variation, but not that much. Any felt or measured weight difference in weight is much more likely (I would think) to come from variations in the process, not from the resins themselves.

I have identified four (actually three) resins out there that are manufactured for stabilizing wood: Stickfast (by TMI), Cactus Juice, BVV PC504/66 (manufactured by Ultraseal), and BVV "American Made" labeled resin (actually re-labeled Stickfast). I have confirmed that K&G does not synthesize their own resin (they are WAY too small for that) ... so they likely use two of these (or something very, very similar). Likely they use the PC504 (as this is the only one with a lower viscosity), and then probably Stickfast (I am assuming they do not use Cactus Juice ). I have looked through the Material Data Sheets and Technical Data sheets (when they exist), and while the exact composition of each of these resins are often labeled "proprietary" - there is no indication of inferior synthesis processes used for any of them. Without further real data, I would have to tentatively disagree with Ben (whose experience I respect greatly) that the resins used by K&G are "better" or "cleaner". I would much more tend to believe that it is there process that is much more controlled that makes the difference.

Ok - regarding backgrounds, I tried to be circumspect ... but you mentioned it, so here goes. I hold a B.S. in Chemistry, an M.S in Chemical Engineering, and a PhD in Chemical Engineering/Materials Science. A lot of my work over the years (30 years industrial experience) has involved polymeric systems very similar to this Acrylic system (and at times explicitly the acrylic systems), and also, both in my PhD work and industrial experience, extensive work in porous materials (un-stabilized wood is a porous material). I have also done a lot of work in the area of the physical/mechanical properties of composite materials (of which stabilized wood is one) this stabilization process make sense to me ... but I can also see clearly how it can be misunderstood and how the stabilization process can go awry. I am interested in helping those that want to do it at home ... do it better (I also want to try it myself!). That is all that this is about.

But again, if I am alone (or mostly alone) in being nerdily interested in this process, I will desist and request the moderators delete this thread.

 

[Greenberg Woods]

But ... HOW do you know (versus just believe) that heavier translates into “better” for your particular needs and use conditions? That is a jump being made here by many with no data, at least as far as i have been able to find... Again - "how good is good enough"?

Why do people use lignium viate for handles? Why is African Blackwood more popular than black dyed maple?

Because the density is directly related to the amount of resin impregnation, and because the density is something customers want. Dense woods feel better in the hand, they make they knife feel more solid.

 

[Cushing H.]

Because the density is directly related to the amount of resin impregnation, and because the density is something customers want

A valid and important point - especially when you are selling knives for $100's and $1000's. I get that. But does it really come down only to that with no exceptions? Is there no room or appetite here to also ask, for the hobbyist and the person making knives for family and friends, whether they can better understand and do the process at home (because it is fun and interesting - not because they are going to make a profit on it), and have a level of assurance that the results are likely to be "good enough" for their purposes?

I am also still somewhat interested (shocked? surprised?) by my experience with my 8yo Shun Santoku with Dymondwood handles, which material has clearly shrunk over time. It was expensive. Just what, really, should we reasonably expect of these composite materials over time (and not just brand new out-of-the-box)?

 

[daizee]

Lignum Vitae has moved more than any other material I've used, stabilized, natural, or synthetic. I think it must be used under compression in boat-building bearing/bushing applications.

 

[Greenberg Woods]

A valid and important point - especially when you are selling knives for $100's and $1000's. I get that. But does it really come down only to that with no exceptions? Is there no room or appetite here to also ask, for the hobbyist and the person making knives for family and friends, whether they can better understand and do the process at home (because it is fun and interesting - not because they are going to make a profit on it), and have a level of assurance that the results are likely to be "good enough" for their purposes?

I am also still somewhat interested (shocked? surprised?) by my experience with my 8yo Shun Santoku with Dymondwood handles, which material has clearly shrunk over time. It was expensive. Just what, really, should we reasonably expect of these composite materials over time (and not just brand new out-of-the-box)?
View attachment 1164500

Well, the dymond wood on your shun is a phenol formaldehyde if I'm not mistaken, not an acrylic product.

And the question of good enough is one you have to answer for yourself. What level of risk are you comfortable with? For my clients, I find they are willing to pay the extra charge of professionally stabilized wood for the added weight and lowered risk. Some people may not be, some have more or less faith in their own product. Make knives with whatever you want to use.

My only issue is people who say that there is no effective difference between woods stabilized professionally and at home, as my wide experience in the subject tells me that home stabilized pieces are in average lighter, and so I disagree with that specific statement.

I dont think knifemaking should be prescriptive. Make what you want, but always be honest with your customers.

 

[Cushing H.]

My only issue is people who say that there is no effective difference between woods stabilized professionally and at home,

I will not argue against that at all ... in fact that is exactly part of what I was hoping to clarify (while still maintaining the "good enough" question) ... but using visible and understandable data.

I do not see people coming out of the woodwork in positive statements for interest in the background - so I guess this is just me being interested in something that others are not. Not the first time that has happened...

I request we just let this thread die. Not worth it if I am the only one interested in talking about it.

 

[kdnolin]

I just recently tried both ways. I sent some to K&G and used 2 gallons of cactus juice. Fortunately, I live a few miles from Willie71 and he loaned me his stabilization equipment. He also shared his experience on the process and I am happy with the results. My CJ blocks sinks in water, but not as quickly as the K&G blocks.

From a hobby perspective, i enjoyed the process, from finding burls, cutting them into blocks and stabilizing them. But as mentioned before, there is not much difference in cost and if this is a business, your time is valuable and probably better spent actually making knives.

Willie71 also told me the dyes for CJ don’t work as well as the K&G dying process. I still had to try a batch, lol, he was right.

Another fact I Learned the hard way, don’t make a vacuum chamber out of ABS pipe, cactus juice will destroy it.

So my conclusion, I used to heat treat simple carbon steel with a torch and canola oil, it works, but Willie71 does it better.
I can stabilize with cactus juice, but K&G do it better. The more I learn, the higher my standards get. So my next batch will go to K&G.

 

[Randydb]

I hold a B.S. in Chemistry, an M.S in Chemical Engineering, and a PhD in Chemical Engineering/Materials Science. A lot of my work over the years (30 years industrial experience) has involved polymeric systems very similar to this Acrylic system (and at times explicitly the acrylic systems), and also, both in my PhD work and industrial experience, extensive work in porous materials (un-stabilized wood is a porous material). I have also done a lot of work in the area of the physical/mechanical properties of composite materials (of which stabilized wood is one) this stabilization process make sense to me ... but I can also see clearly how it can be misunderstood and how the stabilization process can go awry. I am interested in helping those that want to do it at home ... do it better (I also want to try it myself!). That is all that this is about.

But again, if I am alone (or mostly alone) in being nerdily interested in this process, I will desist and request the moderators delete this thread

From a hobby perspective, i enjoyed the process, from finding burls, cutting them into blocks and stabilizing them. But as mentioned before, there is not much difference in cost and if this is a business, your time is valuable and probably better spent actually making knives.

First up, I think Cushing should be teaching us on this subject! Your paragraph helps me make sense of your "nerdy" questions and understand where they are coming from. I am learning a ton from this thread. Especially around the resin and am realizing that in all likelihood that the difference between profession and home stabilization is found in the ability to develop a process and equipment that allows you to produce consistent results. The second factor is experience and knowledge....what resin/process to use with which wood.

Interestingly, this isn't much different from knife making. Knowing processes for different types of steels, and having equipment that allows you to have consistent results. Of course there is the added part of being able to grind, shape, and do all the fit and finish stuff that adds a lot of the final value.

I love process in general. I love finding what looks like a chunk of firewood or a rotting log and drying it and cutting it into blocks and the final look after it is stabilized. Problem for me is that last stabilizing step is so cheap....around $5/block for K&G. Toss it in a box and send it. It's sort of like mosaic pins for me though....you get them because they ad to the "art/look/" of the knife. For me stabilizing is just a necessary step...different to me.

In the end I will find this thread pretty interesting and cool, but I likely will not set up to stabilize myself.