I Did Something Really Wrong

[Stevej72]

I tried casting some more snake skin in Alumilite. I glued corks into the ends of the tubes that were filled with shot for weight. Clear nail polish was applied to the skin as I've had a lot of trouble getting either PR or alumilite to stick to the skin. I glued 3/4 inch square pieces of wood to the ends of the corks to keep them off the bottom of the mold. I mixed my Alumilite by weight, 55 grams of each. Poured the Alumilite into the mold and put the mold in the paint pot and applied vacuum. I tried to turn them just to see how bad they looked but the skin came loose from the tubes so they won't turn even with very light pressure. It is very brittle as the bubble you see on the surface go throughout.

 

[its_virgil]

Steve,
I think you should have used pressure, not vacuum. I never apply vacuum to the resin after it is poured into the mold with the skins. I use vacuum on the <b>resin only</b> then pour into the mold and apply pressure. Of course, I've not cast alumilite, only PR. But, I think alumilite needs pressure and about 60 psi if I remember. Curtis will help out when he sees this post.
Do a good turn daily!
Don

Originally posted by Stevej72
<br />Poured the Alumilite into the mold and put the mold in the paint pot and applied vacuum.

 

[stevers]

Steve,
I was told the same thing. The only time you use vacuum is with resin only, and only to de-gas. I was told "anytime" you put "anything" in the resin, you only use pressure. Be it cactus, worthless wood, snake skins or anything of the sort. All these things can hold hidden air, using vacuum will pull that air out and into the resin. And with a resin that sets as fast as Alumilite, it doesn't have enough time to remove all the air. Even with PR you don't have enough time to remove air before it starts to gel.
Next time try it with pressure. I just put in my first cactus and will be anxious to see how it works. I put it under 40 pounds of pressure. I realize this may be excessive on the pressure, but I'm not taking any chances.
Let us (me) know how the next one comes out Steve.

 

[MesquiteMan]

Steve,

You have a moisture issue somehow. Maybe your skins are not as dry as you think they are. Maybe the chemicals they used to tan the skins is somehow reacting with the Alumilite but that many bubbles is very indicative of moisture.

Also, skip the vacuum all together when using Alumilite. You can cast Alumilite with vacuum without any problems but I just feel it works better with pressure. The vacuum IS NOT your problem in this case. If you feel you really need vacuum (I don't use it at all with my cactus) then run the vacuum on part A and then part B and then mix. Once poured, use pressure. Alumilite recommends 30 psi for regular castings I believe. I use 60 psi when I am doing anything that has a lot of nooks and crannies such as cactus or WW.

 

[airrat]

I had the same problem Steve and as Curtis said it was moisture. Alumilite does not like any moisture.

 

[Stevej72]

Hey everyone, thanks for all the input. Curtis did tell me before to make sure what I was casting was dry. Not sure how to tell if the skin is dry though, I guess I'll leave a piece out in the air for awhile. Next time I will only use pressure.