Epoxy vs Resin

[Dick Wilson]

I have a piece of Euc. Gum Burl that I want to fill major voids. I have used epoxy in the past but never 2 part resin. What is the difference without me having to run out and get a Chemistry degree? What can you use to color the epoxy/resin?

[Mike Hollingsworth]

To color, I use the slightest bit of artist's oil paint from all the colors at an art supply store. Windsor Newton, Grumbacher etc. Just a tad on the end of a toothpick. I've got black, white and about three browns that will last my lifetime.

[Alan Trout]

Dick,

They are both resins. If you are not pressure casting or vacuum casting the piece you are probably better off with tinted epoxy as bubbles can be an issue with other resins. I use Polyurethane resin as is does not shrink any great deal which epoxy is about the same on the shrinkage. Polyester resins shrink to much in my opinion with mixed material and can separate from the wood.

Good Luck

Alan

[Jamie Buxton]

Resin is a broad term that generally includes epoxy. Resin (and epoxy) are generally two-part products. Behind epoxy, the next most common resin is polyester. Polyester is often used for fiberglassing, because it is substantially less expensive than epoxy, although epoxy is used there too. Generally the retailers of resins also sell pigments. They're little bottles of additives for the resing that add color. I've also read that you can pigment resins with universal colorants. They're the pigments used to color latex paints. You can buy bottles of them at full-line paint stores, but the bottle are big enough to be a lifetime supply for little projects like you're talking.

[James Combs]

Dick,They are both resins. If you are not pressure casting or vacuum casting the piece you are probably better off with tinted epoxy as bubbles can be an issue with other resins. I use Polyurethane resin as is does not shrink any great deal which epoxy is about the same on the shrinkage. Polyester resins shrink to much in my opinion with mixed material and can separate from the wood.
Good Luck
Alan

What Alan said. Plus when comparing epoxy resins vs the polyester resins if adhesion to wood is a consideration always go for epoxy. I don't recall where I read it but just in the last couple weeks I read what sounded like a very authoritative article on epoxy verses polyester on wood. Apparently the polyester just kind of sits on the top surface of the wood whereas the epoxy actual links molecularly to the wood cells/fibers so it is a much stronger connection. I believe I read this in the boat forum.

[Curt Fuller]

What is the difference without me having to run out and get a Chemistry degree?



Basically the consistency or viscosity, whatever you like to call it. Epoxy is thicker, usually used as an adhesive, resin is thinner, usually used to cast something.

[Russell Neyman]

When comparing epoxy resins vs the polyester resins if adhesion to wood is a consideration always go for epoxy. I don't recall where I read it but just in the last couple weeks I read what sounded like a very authoritative article on epoxy verses polyester on wood.

I did not realize that polyester was a resin used in woodworking. Learn something new every day.

[Jim Burr]

I only use PR resin for pen casting. The shrinking allows it to pull away from the mold sides...not something you want in a turning!! It is also prone to bubbling and is really runny. The varying cure time based on temp/humidity/freshness and amount of catalyst used makes it really unpredictable. You can speed up the cure time with more catalyst, but the resin get very chippy and requires very small cuts. I've used Devcon epoxy on several peices and use Pearl Ex powder for coloring...possibilities really are unlimited!

[Jamie Buxton]

I did not realize that polyester was a resin used in woodworking. Learn something new every day.

Bondo is a standard tool for painters around here, and is sold in the paint section Home Depot and the like. (Bondo is usually sold for repairing car bodies.) They use it to restore the elaborate woodwork on the outsides of Victorian buildings. They cover it with paint, of course. Bondo is polyester resin, thickened to putty-like consistency. It does bond to wood quite securely.

[Norm Zax]

Gentlemen, gentlemen, some of you are mislead. Resin is the glue like substance that constitutes the main component of paint (or glue, or nail polish or...). It is either clear (such as in Acrylic resin) or amberish (such as in Polyurethane resin and most other resins). It can be single component (drying by oxidation and crosslinking) or double component (drying by reaction between the two chemicals mixed). Additonal resins not mentioned: polyamide, alyd, shellac and many more.
[originally, resin was the name given to the secretion of coniferous trees]

[Dick Wilson]

Gentlemen, gentlemen, some of you are mislead. Resin is the glue like substance that constitutes the main component of paint (or glue, or nail polish or...). It is either clear (such as in Acrylic resin) or amberish (such as in Polyurethane resin and most other resins). It can be single component (drying by oxidation and crosslinking) or double component (drying by reaction between the two chemicals mixed). Additonal resins not mentioned: polyamide, alyd, shellac and many more.
[originally, resin was the name given to the secretion of coniferous trees]

Thanks everyone for your input. I should have attached a picture to begin with.:( So Norm, I want to fill the obvious voids in this burl 209234I plan on using craft paper to glue all the way around the burl forming a "mold". Whatever I use I want to add color before the pour. What would you use.

[Chris Burgess]

I am no expert but here are my thoughts. I would try something thin that would flow into the wood. Alumilite resin may be the best thing. You can warm it to make it run and its shrinkage is minimal (so i've read). PR would be tough and you would sure want to put it under pressure becuse you want to pour it in thin but PR shrinks. I cast pens and I will pour 2oz of PR and let it thicken before pouring in the mold. By the time I pour I have lost some volume. I would expect this shrinking to cause the PR to pull away from the wood as it dries.

[Alan Trout]

You should never warm Alumilite. I refrigerate my part A to slow down the cure rate. If you warm the resin It was speed up the cure rate to much and you will be in big trouble. The only way to do that piece in Alumilite is to pressure cast it to prevent bubbles and also you need to leave space around the piece to allow the resin to flow. I would guess that could take $30 to $50 worth of resin doing it the way I do my casting. Just guessing at size compared to sawhorse.

Alan

[Jamie Buxton]

Thanks everyone for your input. I should have attached a picture to begin with.:( So Norm, I want to fill the obvious voids in this burl 209234I plan on using craft paper to glue all the way around the burl forming a "mold". Whatever I use I want to add color before the pour. What would you use.

Resins -- either polyester or epoxy -- intended for fiberglassing are nearly the consistency of water before they cure. I use West Systems epoxy that I get at a local marine-supply store. I think Woodcraft sells it, or maybe System 3, which is the same stuff as far as I can tell.

[Norm Zax]

Im with Jamie. Choose something with with low viscosity and as cheap as you can. With those small voids you may get air trapped anyway.
Post some post-production pics!
Good luck

[Jim Burr]

Respectfully Jamie...your view of resin viscosity is a bit off. If using PR Cast & Craft from Michaels or similar...it's hardly water. With a cool oil consistency, once the catalyst is added, it will harden anywhere from 5 to 20 minutes. For pen casting (done on an almost daily basis) PR is warmed to accelerate an exothermic reaction...about 150 degrees. This also helps to mix colors if that is a goal. Filling voids with PR is a bad idea unless a vacuum or a pressure pot is used...the mixing of catalyst creates bubbles and can't fill voids in "worthless wood" without pressure to minimize the air bubbles. Additionally...PR shrinks...a lot! Filling molds is easy since the PR shrinks and pulls off the sides. Vacuum stabilizing with Cactus juice or similar low vac pressure stabilizer will really help with softies. Filling voids is best done by substantial vacuum in a continual pressure environment for a prolonged time.

[James Combs]

Thanks everyone for your input. I should have attached a picture to begin with.:( So Norm, I want to fill the obvious voids in this burl 209234I plan on using craft paper to glue all the way around the burl forming a "mold". Whatever I use I want to add color before the pour. What would you use.

Dick are you planning on turning the burl into a vessel after "molding" it? The rest of this post assumes that that is the game plan. If it were me I would rough turn it first before molding and then build a mold around the rough shape. That would save a significant amount of resin regardless of the resin type. Check out Dave Bell's "Bowl Casting 101" (http://www.sawmillcreek.org/showthread.php?171950-Bowl-Casting-101) for a how to.

[Jamie Buxton]

Respectfully Jamie...your view of resin viscosity is a bit off. If using PR Cast & Craft from Michaels or similar...it's hardly water...

You didn't notice that I said "resin intended for fiberglassing." Resin intended for fiberglassing is set up to completely wet the fiberglass mat. It is made to wick into tiny spaces. The brands I cited really are quite fluid. That said, you're right that dunking the OP's chunk of wood in epoxy is not likely to completely fill all voids. There may be bubbles trapped inside, and there may be cavities in the wood that aren't presently open to the air. Without a vacuum system, the best he can do it is to fill the blank as best he can, turn it, and then fill any revealed holes with more resin.

[robert baccus]

2 part resins are also useful for saving weak rotten spalted wood. mix the 2 part resin and add just enough acetone to thin it somewhat. place your piece in a black VINYL bag, pour in the resin and shake it every time you walk by. i always rough off any excess wood beforehand. wait overnight and observe the ugliest chunk of wood ever. when you turn the wood you will discover the resin is only in the vessel walls and the wood looks and feels like brand new. cuts like it too. if you cut through the resin just repeat but the process is easier than describing it. you can literally do this to a roll of toilet paper if you can find any with pretty grain. good luck------------------old forester