WWA Info Exchange

Kinda WW'ing related but ....

I've been experimenting casting wood shavings in epoxy with the thought of turning something out of the result. I'm ending up with more than a few bubbles encapsulated in the end product. I've read that thinning the stuff has an effect on the strength of the bond which I would translate into reducing the hardness of a cast block. What trade secrets can you share for eliminating these bothersome bubbles?

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Nullum Gratuitum Prandium

Cheers - Dennis

I have no direct experience, but I've been told you can help the degassing of the epoxy with a vacuum pump. If you have a vacuum clamping setup, just use the pump to draw a vacuum in a container that has your epoxy/wood shaving mold in it. Not sure what sort of container won't collapse, but I'd be real cautious about trying glass.

I used some envirotec and the directions said; if there are bubbles in it, pass a blow drier over it and the heat will bring the bubbles to the surface and they will disappear.
It worked for me.

Wayne

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WW'ers I have met.
Guroo
Verna
Wooder
Paul, (brother,)
Falcon1.
Gene and his friend George

Yeah, I would try heat. Though I'm not sure how well it would work for thicker pieces.

I used a propane torch on these inlays (which are tinted epoxy):



You could probably use a heat gun or a blow dryer or a torch . . .

-Brian

http://content.penturners.org/articles/ ... urepot.pdf

The HF paint pot is a very common device used by cast acrylic turners. I bought one a while back when it was on sale (and with a coupon) but haven't assembled it yet.

The theory behind reducing bubbles is explained here

http://www.penturners.org/forum/showthr ... ht=bubbles

I believe that nailer may have much more experience with this and may be able to assist better than I

Hope this helps--
Lawrence

Heating to thin it can work, but the risk is that epoxy gives off heat as it cures. The faster it cures, the more heat it gives off and the faster it gets... If you have too thick a section and the epoxy is fast enough, it will heat up enough to char. That's kind of interesting to see, but not likely good for your project.

The solution to casting is to use a relatively slow cure epoxy that is thin enough without heating. One such epoxy is System Three clear coat. (Another company's clear coat is NOT the same kind of thing.) It is very thin, so bubbles come out easily, cures fairly slowly, and is possibly the clearest, most colorless epoxy available. It has lots of uses.

Thanks everyone for the replies and suggestions. Heat is out with my current material since it's a fast setting Systems 3 formulation. The clear coat stuff sounds like it might be the better material.

I know, no pictures, etc., but in fact, nothing has really happened yet anyway!

To be continued...

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Nullum Gratuitum Prandium

Cheers - Dennis

Another vote for System 3. We did the canoe with it. Very forgiving for a first timer. We used System 3 Silver Tip Laminating epoxy, but it sounds like the System 3 Clear Coat might be what you are looking for.

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Tim Eastman
Lead by example - be an example worth following

Used West Systems epoxy for some thinner stuff 1/4 thick but no
bubbles. Stuff is pretty thin to start with.

Duan

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Duan Packard
Kerrville, Texas

dum vivimus, vivamus

Use a finishing sander to vibrate the castings.

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"It is not a mistake it is a learning experience"
Monte

Cool idea, Monte! Thanks

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Nullum Gratuitum Prandium

Cheers - Dennis

Lawrence -
I checked your links and saw interesting ideas on using a pressure pot, but I didn't see an explanation of why it works? Did I miss something?

Anyway, it looks like these serious pen-turner/casters use the pressure pot for both pressure and vacuum. I'm guessing they use the pressure mode when stabilizing wood, as the pressure would force the resin into the pores. They also use a vacuum mode, which I believe is to encourage outgassing of the resin, consistent with what I conjectured at the start of this thread.

You probably already know the risks about epoxy.
Me?I was told off by the health and safety person at work.
(My students uses it to glue knife handles.)
Protective rubber gloves must be worn and all work must be direct under a ventilation funnel.
I contains very nasty stuff apparently... But so do most things in life.
/Anders