Air bubbles

[WildBill]

I was hoping one of the more experienced castors might be able to help out. I'm getting small random air bubbles in my casts. I've been using a syringe to inject the 305 into my molds. I do have an inlet and outlet for air. If I flow more product through the mold instead of just filling it, will I eliminate the air bubbles? Are the air bubbles out gassing from the curing process or just trapped air from mixing?
I don't have a vacuum chamber.
Thanks!
RJ

 

[daremo]

Are you using a pressure pot? I found that no matter what I tried, bubbles forming in the casts were inevitable without a pressure pot. It sometimes helps if you "massage" the molds and open the mold to let the resin in and the air out. I do that before placing the molds in the pressure pot. If you squeeze the mold and bubbles are coming up, you still have air in the mold that needs to get out.

 

[G.I.*EDDIE]

Put the mold on something that vibrates to work the bubbles out.

 

[WildBill]

I have no pressure pot either...but I could weld up a pressure vessel and use compressed air.....
I'll try and rig up some kind of vibration pad and see if that helps.. Thanks fellas

 

[Giga Bread]

Just go the paint pressure tank route.

Bubbles can also form if you're using wooden utensils to mix. Air and moisture have a tendency of getting in when stirring. Make sure if you're reusing syringes, that you dry them out completely before reusing. Humidity contamination to your resin can also create bubbles.

 

[WildBill]

I have been using bamboo sticks to stir! I will try something else