First 3 attempts at casting a disaster

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theoreed

Member
Joined
Aug 16, 2021
Messages
7
Location
McCool, MS
I live in Central Mississippi where there is high humidity and have tried 3 times at casting but each one has come out looking like the top of the cast is milk, I'm sure it's the humidity causing the problem so I'm seeking advice on what I can do to help correct the problem. I've used both Alumilite slow and regular and have the same outcome. Any suggestions?
 
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I've only got 8 castings (two batches) under my belt but I had a small trail of what you describe on my first cast (that I was able to turn away). The second was perfectly clear. The advice I got was I didn't mix the first batch enough so I made sure I mixed the second batch well.
 
Not sure if the mixing is a problem or not. You do need to mix until there is no visible swirls in the mixture. If whatever you are using for coloring is water based it will cause issues and can foam and make a mess. I don't think humidity is an issue, I live about 10 miles from the Pacific Ocean.
 
I don't know how many blanks your pouring at a time but Using small amounts of resin can be more difficult than larger amounts, reducing the room for error in your ratio of equal parts. Usually the top of a pour will be milky because it's harder to mix the resin against the sides and bottom o the cup. Side B is thicker and can often leave swirls of unmixed resin in the cup. I would suggest warming side B with a light bull to around 90-100 degrees (measured with a digital laser thermometer). This will allow it to mix easier and quicker. If your worried about heat and working time, put side A in the refrigerator to cool it down. It won't thicken like side B. Next, take a spade drill bit and break the tip off. Round the sharp edges on a grinder or belt sander and use it in your electric drill to mix the resin. Don't worry about the air bubbles when mixing, the pressure tank will take care of them. Just pour a little extra resin in the mold since it's depth will shrink a little as the bubbles are compressed. Also be sure to keep notes as you work out your issues so you can look back if needed. You'll get it worked out. Good luck and happy casting!
 
Another thing to check is moisture in your compressor. Make sure you have some sort of inline filter to stop moisture from entering the pressure pot. I had the same issue up until I installed a filter.
 
Read John U's reply carefully! The white milky casts with Alumilite Clear and Clear Slow (their urethane resins) is definitely either an incorrect ratio or incomplete mixing. His reply is spot on. It is not a moisture problem, Moisture in these two resins cause foaming and not the white milky color. Scrape the sides, bottom, corners and then scrape and stir more. Use only one mixing cup. Do not measure into two cups and then add one to the other. The sides of the cup need to be smooth with not grooves or rings.
Do a good turn daily!
Don
 
Thanks to all who responded, I appreciate everyone's advice. I'll try another attempt at casting next week when I have shop time and will post the results with pics if something goes wrong.
 
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