Epoxy Resin?

[Pollock]

Have any of you ever tried suspending wood in epxoy resin and then turning it? If so, what products/processes worked best for you?

Thanks,

-Steve

 

[Groundhog]

epoxy information

I have use epoxy for clear finish on cedar strip kayaks. The only thing I can tell you that the type of hardener is important to atain a clear finish. I used west system epoxy. You can call Gougeon Brothers, Inc. at 866-937-8797 ask for tech information. They are very helpful. You will have to seal the wood before in goes into the epoxy because of the out gasing that will happen. Hope this is helpful.

groundhog

 

[Ed_McDonnell]

I'm not sure what size you are contemplating, but a lot of penturners create their own custom blanks using clear casting resin. The pen blank castings are typically only 3/4" to 1" thick. If you were thinking about something 6", 12" or even thicker you will have a number of problems to overcome but it should be doable.

Ed

 

[Ed Davidson]

I've done all kinds of resin stuff. The largest casting I tried was about 7" x 4" x 2" for a friend who wanted something special to carve a bow handle out of. These are all cast and lathe-turned polyester resin, like the pen turners use.

 

[Angelo]

Resin

Ed,

What is the brand of resin you use? Do you put it in a vacuum to remove the bubbles?

A

 

[Ed Davidson]

There are a half dozen or more brands of PR that I'm aware of. It’s used a lot in the boat building and repair industry. The one I use is called Clear Cast and is intended for hobbyist. I think the formulas for each of the brands is somewhat different as some smell much worse than others and some disburse bubbles better than others. I've poured about 240 gallons of this stuff so far, all without using a pressure pot, and have not had a problem with voids or bubbles.

There is one exception however, where a pressure pot might come in handy…that's when natural materials are cast in the resin, like cork, leather, cloth and some painted surfaces...just about anything that has a delicate or porous surface. The curing process generates heat, and these natural materials will sometimes "outgas" or corrupt, causing unpredictable results.

I also suspect that room temperture and humidity have an effect on the casting process, mainly in the time required to cure and the amount of hardener needed. Lots of variables to consider…

 

[Ed_McDonnell]

Castin Craft and Silmar are the ones I remember now. Prices are pretty variable, so shop around. You should be able to get clear polyester casting resin for $30 - $40 a gallon. Typically the catalyst is included at no extra charge. Look around in art/craft stores, model shops, fiberglass resin dealers (if you are luck enough to live in an area where boating is popular) and the internet.

If you do a little research on the web (and you should) be aware that there are different types of clear casting resins (polyester, polyurethane, epoxy, other?). They all have different properties and requirements, but frequently people don't identify the actual resin type they are working with in their comments. My comments below are all related to my experience with polyester resin.

I didn't find vacuum necessary for what I was doing. If you decide you need it, your mold should be at least five times the size (height wise of course) of the pour volume. You only have a limited time to apply the vacuum, but if you pull too much too fast you'll learn all about exploding foam. That foam and the internals of a vacuum pump don't mix well. You also need to limit the vacuum so you don't vaporize some of the components of the resin (essentially low temp boiling).

I have found application of pressure useful in some cases. 20-30psi.

Pressure and vacuum should only be applied using appropriate equipment. You can kill / maim yourself / others if your vacuum / pressure vessel fails.

Polyester resins are different than epoxy resins. Even if you are an expert on epoxy resins, do some tests with the polyester resins first. Polyester resins use a catalyst. Epoxy resins use a hardener. The ratio of catalyst to resin is not as critical in polyester resins as the ratio of hardener to resin is in epoxy resins. This is good news and bad news.

The catalyst creates heat which is what cures polyester resins. More catalyst = more heat. Larger volumes (thicker) also means more heat. Molds that act as insulators mean more heat. Too much heat will cause undesirable results. You need to adjust the amount of catalyst to compensate for volume and mold properties.

As with any resins, protect yourself from fumes and skin contact.

Good luck and be careful.

Ed

 

[Ed_McDonnell]

Ed (yoyospin) - I just noticed the EPR blanks on the Arizona Silhouette site. Looks like you are having a lot of fun. You're going to have to sell a lot of pen blanks to pay back that 200+ gallon learning curve investment.

I can just imagine the look on my wifes face if I tried to wheel a 50 gallon drum of that stuff into my shop (aka the garage).

Good luck with the EPR blanks.

Ed McDonnell

 

[Jon]

Plasticizer for PR?

Ed (yoyospin) -- In all your experiments with PR, have you ever tried a "plasticizer"?

I was experimenting with PR but had a lot of trouble with it being too brittle. Especially when I tried to do things like threading, or when someone dropped a piece (damhikt).

A South African guy mentioned he added a "plasticizer" and I looked for sources. The only one I found was at Douglas & Sturgess (aka ArtStuf.com). Here is a link to the minimalist description of the material: PR Plasticizer

I moved on to ER's to experiment, but there are another whole set of issues working with epoxy. If I could have a more forgiving PR, I'd go back.

Curious,

--Jon

 

[Ed Davidson]

You might try this stuff: Gel Promoter. It REALLY stinks but does work well.

PR "brittleness" is a common complaint. Using less catalyst (less heat) will help. Using the right tool helps as well. Have you seen any of my PR turning online video tutorials? Dial in here and look on the left-hand side of the page for a list of How-to's