Failed casting

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U

Ulises Victoria

Member
Joined
Oct 11, 2011
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534
Location
Monterrey Mexico
Hello all. I cast a couple of El Grande blanks last night. I made the design I wanted over the tubes, using paint and gold leaf mostly, and then applied 2-3 coats of medium CA to protect it.
I then put the blanks in the molds, mixed the resin in a cup immersed in a pot with hot water, and pour the resin in the molds. (The molds are 1" pvc tubes)
Next morning, I saw something like a giant bubble inside both of the castings.
I suspect the CA released gases while the resin was hardening. At last I don't find any other explanation. Any insights from the knowledgeable people here? If my suspicion is true, how long should I let the CA to cure to be absolutely sure I will not have this problem in the future? Any way to "accelerate" the curing process?
Would a pressure pot (or is it vacuum???) help with this? If so, any recommendations?
As always, thank you very much for your time!!!
 
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If you have plugs plugging the ends of the tubes, some air may escape from the inside of the tubes past the plugs. Because the resin is getting harder now the bubble becomes bigger and does not float to the surface. I think CA gassing may leave tinny bubbles on the surface of the work. I have done a few casts where everything is fine when I left. When I came back there were big bubble voids where the plug had loosened (even though I had inserted them with more then enough pressure) and air leaked out of the tube. I now lightly clamp the plugs in.
 
Ruby pen turning said:
If you have plugs plugging the ends of the tubes, some air may escape from the inside of the tubes past the plugs. Because the resin is getting harder now the bubble becomes bigger and does not float to the surface. I think CA gassing may leave tinny bubbles on the surface of the work. I have done a few casts where everything is fine when I left. When I came back there were big bubble voids where the plug had loosened (even though I had inserted them with more then enough pressure) and air leaked out of the tube. I now lightly clamp the plugs in.
Click to expand...

Yes. I used wooden pegs to plug the holes, and put a piece of plastic bag to "seal" the wood peg against the tube. I think maybe the plastic wrinkled and left small openings where the air went out. Well... I'll have to keep experimenting to see what works best.
Thank you both for your answers
 
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I would add that the wood plugs probably didn't help with the air issue either. Get yourself some silicone rubber plugs from Argon, totally reusable and easy to push in the tubes. Pressure will shrink the air in the molds. I use it all the time but can't comment on vac since I haven't used it much. Good luck and keep at it.
 
JohnU said:
I would add that the wood plugs probably didn't help with the air issue either. Get yourself some silicone rubber plugs from Argon, totally reusable and easy to push in the tubes. Pressure will shrink the air in the molds. I use it all the time but can't comment on vac since I haven't used it much. Good luck and keep at it.
Click to expand...

Hmmm... I was thinking about filling the tubes with something like sand, sugar, even water, etc. This may work, don't it?

Do you have a link to those Plugs from Argon, John?
Thank you!
 
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Not water! I have used clay...play dough to be exact. The clay replaces air. Plug one end, pack in the clay and then plug the other end. Getting a good seal is essential. Silicone plugs are the way to go. Wood has air in it and the air will escape when heated from the curing. Eleminating air sources is the best thing that can be done.
Do a good turn daily!
Don

Ulises Victoria said:
Hmmm... I was thinking about filling the tubes with something like sand, sugar, even water, etc. This may work, don't it?
Thank you!
Click to expand...
 
Thanks.
Could someone please post a link where to get those silicone plugs? Searching for "silicone plugs" in Amazon yields mostly ear plugs among another zillion things. Which ones are specific for what we need here?

TIA
 
JohnU said:
I would add that the wood plugs probably didn't help with the air issue either. Get yourself some silicone rubber plugs from Argon, totally reusable and easy to push in the tubes. Pressure will shrink the air in the molds. I use it all the time but can't comment on vac since I haven't used it much. Good luck and keep at it.
Click to expand...

John,
Which Argon plugs do you recommend?
 
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