Alumilite *LINK*

Air bubble control

Dick Coers

The pen turners that cast with Alumilite use a pressure vessel to remove the air bubbles when casting. It kicks so quickly that bubbles don't escape, which is likely an issue with just filling voids if they are pretty big. I don't have any experience with it, just read the info and watched a couple of demos. Low odor is a major bonus, and I guess speed would have an advantage for continuing with the work. Getting the proportions right when mixing really small batches, air bubbles, absolutely any moisture in the wood can cause foaming issues, and I think a somewhat short shelf life because of the larger containers, are some issues of concern.

Re: Air bubble control

John C Lucas

I fight air bubbles no matter what resi. Or epoxy i use. I havent tried vacuum yet but may look into it.

Ive been weighing my resin parts to get accurate amounts of resin and hardener using an old digital scale i used to weigh photo chemicals (remember those). I was told it wouldnt work with west systems bjt ive been doing it for years with great success. The only one i dont do by measuring is Inlace which requres X number of drops per ounce.

Re: Air bubble control

Stuart Johnson

From watching Youtube videos it sounds like pressure works better. Zac Higgins https://www.youtube.com/user/NVWoodwerks/videos has some good ones.

Re: Air bubble control

John C Lucas

I have a jeweler criend who uses thickened epoxy in her work. She has bubble oroblems and we experimented woth carious things. Vacuum worked on thin epoxy but not very well on thickenend. Pressure simply made the bubbles smaller bht didnt necessarily get rid of them. Her work is quite small so bunbles really show. What Marilyn Campbell suggested worked best. After you mix it you spread it out on a piece of glass fairly thin which releases the bubbles. Works great for ber work and some things ive done. Not so great for normal.viscosity epoxy that we tend to use to fill voids

Re: Air bubble control *LINK*

Dave Paine

I have also struggled with bubbles in some epoxies, like System Three.

I had better luck with another Aluminite corp product called "Amazing Clear Cast".

I am now using Smooth-On resin ExpoAcast A690. This had low heat and so far has set with zero bubbles. This resin is a long pot life, but others in the series have shorter pot life.

The Smooth-On resins are mixed by weight. I now find this more accurate then measuring.


https://www.smooth-on.com/products/epoxacast-690/

vacuuming epoxy

John K Jordan

When I ran a small metallography lab I used a little dome-shaped vacuum chamber to get the bubbles out of samples potted in epoxy. It took a while so the epoxy was a slow-setting type.

It's been 40 years but I think I just kept the vacuum on until the bubbles stopped. I never tried it with wood.

I was preparing samples cut from nuclear reactor elements - good fun! Even tiny bubbles were bad since they created voids that collected grit and diamond compound. Try preparing something for the microscope when the even a single piece of grit from a previous step falls on your polishing disk!! Even after the vacuum treatment I used an ultrasonic tank for cleaning between each step. Maybe all that made me extra sensitive to sanding scratches today.

JKJ

Re: Air bubble control

Peter Hyde

Something overlooked when trying to control air bubbles in epoxy is the mixing speed. Mix very slowly, don't beat it. Then because there is an exothermic reaction during set up the heat produces will encourage any air trapped in the wood to expand and form bubbles. Solution, make sure the wood is warm before applying resin. This will also thin the resin and giver better penetration and adhesion. Also if possible wet the wood with a very thin coat of resin and allow to set up, then wash surface with white vinegar to remove any blush. This effectively seals any air into the wood and reduces bubbles. Either way will work.

That's the issue with Alumilite, time

Dick Coers

The clear casting variation used for pen blank casting kicks very quickly. They tell you to mix the dye in before mixing in part two to get a consistent mix. If you stir it slowly, you'll have a popsicle.

Re: Air bubble control

John C Lucas

I will have to try wetting the wood. Good tip. I was trying to cast some wooden mini goblets into clear casting resin. Every time i did it the goblets were covered with micro bubbles. I decided i liked that because it made the goblets look like they were possibly co ered with a protective layer and they were supposed to be in a womb.

Re: Air bubble control

Steve Worcester.

I have used Alumilite in clear and water clear and polytek polyoptic clear. I haven't used much coloring, but a lot of clear for pens and clear vacuum chuck forms.

I have always used pressure, I weight each part, mix for a minute or two, then into the pressure pot. Pressure has to be above 60#, indirect so it doesn't shoot air directly onto the form, and held for about,20 minutes (depends on the resin).

If you take the pressure off early, the form will,distort. Using vacuum will increase the t]exothermoc reaction and usually lead to foaming and more bubbles.

There are different mixes available that will give you more open time, but with no colors, I never found it neccesary