Poliester resin impregnation in porous woods - Tutorial

No problem Dan! :)

Thanks all!

Phillip, I get it from different places, all big industry related, I have no idea where to get it in the US.
A place that sell equipment to repair boats made of fiber would be a good starting point if you can't easily get it on the places you mention.

Ariel
 
Which one would be best? There's a bunch there, and I don't know much about this subject...
 
Great piece of info. We have some great mesquite root down here but it's too soft or brittle for scales. I've been trying to resin impregnate w/o the vacuum pump to no avail. Thanks again.
 
ArielSalaverria said:
Folks,


It is NOT epoxy resin. It's Polyester resin, as it's more liquid than the epoxy one. Epoxy doesn't get liquified enough (at least with the epoxy resins I have access locally)

Polyester resin, diluted to be liquified enough (10% SM).

The entire piece gets resinated, so you can do whatever you'd like with the finished piece.

6 minutes. I can't use epoxy resin as it doesn't get liquid enough.

Regards :)

Ariel
Click to expand...

I happen to build boats as a hobby and I sometimes need to do restorations that require the use of very thin epoxy that will saturate the wood fibers to reinforce them, in essence very similar in technque to what you are doing here. I have a couple of tips that may help anyone trying to get the maximum viscosity and solubility out of epoxy or polyester resins.

First; Use "SLOW" hardener, you will need to heat the resin in order to thin it, if you use "FAST" hardener you will accelerate the exothermic (Chemical Heat) reaction and it will start to harden before it is absorbed sufficiently.

Heat the piece of wood or other porus material you are attempting to impregnate with resin. This purpose is twofold, it opens the pores of the wood slightly and will aid in driving any moisture out of the block. I would not go crazy here, just put it in a piece of aluminum foil in your wifes toaster oven you have sneaked out to the garage for an hour or so. If you don't have a toaster oven, just do it in your stoves big oven, failing that, use her hair dryer on high heat, making sure to thoroughly heat the block. 200 deg. Fahrenheit is more than enough.

You can heat the resin in several ways, first is a double boiler setup, just get some water boiling and bring the hot water out to your shed or shop in a coffee can or something. Have your vacuum setup all ready to go, once you mix the resin and hardener time is important. DO NOT CHANGE the ratio of resin to hardener that the mfgr. recommends, most will tell you NOT to thin the ratio. I agree, it weakens it's chemical strength and in some cases will cause it not to kick-off , worst case scenario is you will be left with a tar like consistency that you will have to remove, best case; it will work or appear to work, but it will never reach full hardness. Here we go, mix the resin and hardener, dip it into the hot water and stir, take it out of the water and stir it for 2 minutes at a minimum, not more than three minutes, this is critical, critical, critical! Dip your mixing container into the hot water every 15 seconds or so, you will see the resin start to thin dramatically as it warms up, if you dont have any hot water just gently blow hot air from a heat gun or hair dryer around the perimeter of your mixing container and aim it 2-3" from the top of the resin, careful you dont blow it out of the container. Most people make the mistake of not stirring the resin and hardener properly, this applies to ALL epoxy and polyester resins.

The bottom line is heat the block of wood, heat your resin and hardener mix, have your setup ready to pull vacuum before you mix the epoxy. You will be amazed at how water thin the resin will get when you warm it up. I use "West Systems" and have never been disappointed with its performance.

Here is the basic difference in working properties of Epoxy and Polyester Resins that are very important;

1. Polyester Resin will EXPAND some as it set up and eventually shrink as the VOC's (Solvents) evaporate out of it. If you use polyester resin to seal cracks in something that is already cracking you may cause more damage than was originally present as it runs through this minute, yet perceptible expansion/contraction cycle. Polyester resin requires oxygen to cure, epoxy resin does not.

2. Epoxy Resin WILL NOT expand as it cures, it will remain exactly the same size and volume as when you mix it. Epoxy resin will cure rock hard in a vacuum. There are no solvents present to evaporate, it is a WHOLLY chemical reaction not dependent on oxygen. Your block will cure in the vacuum state should you decide to let it, start with an over sized piece and cut if to size on your band saw or table saw.

Given the properties of Polyester or Epoxy resins it should be clear that EPOXY is the only logical choice, if you have a 40 foot sailboat you are trying to re-fiberglass cost may be a factor here, a quarter ounce in knife building or wood stabilization the choice should be obvious, polyester resins are "Old Skool" and economy would be the only reason I can think of to use it, modern Epoxies are without a doubt a superior product.

Regular old white vinegar is an awesome Epoxy solvent and wont kill brain cells or dry your hands out! Try it! You will be surprised like I was. An old boat builder trick.



Enjoy!

Jerry
 
ariel can you please go over trh intial tubing connection. what/how did you get the tubing connection on there? it has tight be airtight ( the connection going into the wood) before you run the pump? I just dont understand exactly--can you explainit to me exactly what it is you do in this part---pretend im very very unsmart--thanks bro-markez
 
marekz said:
ariel can you please go over trh intial tubing connection. what/how did you get the tubing connection on there? it has tight be airtight ( the connection going into the wood) before you run the pump? I just dont understand exactly--can you explainit to me exactly what it is you do in this part---pretend im very very unsmart--thanks bro-markez
Click to expand...

It's just a threaded female / screwing male gig :) It doesn't need to be 100% airtight, but it needs to be threaded, it won't work properly if you don't thread it.

As for Tractorshaft's post, if you can get liquified enough epoxy resin, please use that, I can't get that here. For the record though, I've been using poly resin for many years and it just stays still and workd for my intended purposes.

Ariel
 
I was looking at having some staghorn sumac stabilized for the purpose of knife handles and game calls, in you opinion does the moisture level in the wood make a difference?
 
For those of us in the US, US Composites is where I buy my polyester resin. Silmar 41 is my favorite, though I haven't tried stabilizing with it yet.

Only around $40 a gallon IIRC.
 
i have a pressure pot.
how would i go about using that?
i have been using the walnut looks similar to the nut tree you were talking of.
i really love the look of this wood,but would likje a better way to fill it.
i tried some clear nauil polish on the top,but know that isn't gonna fill it thru.
looks great on the surface though,
thanks for the great tut,
jd
 
You must log in or register to reply here.
Back
Top