Alumilite clear slow problem?

[RGABEL]

I finished a casting the other day with some new Alumilite Clear Slow resin. I noticed that my leftover resin in the mixing container dried white. Luckily I was doing a color casting so the end result was fine. I am planning on some clear casts in the near future and am concerned that there may be an issue with my resin. Never had this happen before. The bottles look correct, the part B is clear not the "yellow" that Alumilite white is. Any thoughts?

 

[Kenny Durrant]

Either not pourd to the correct amounts or not stirred properly. Each part needs to be pretty accurate on equal weights. It also needs to be mixed well. Be sure to scrape the sides and bottom when mixing. If there's some that's still dripping down off the sides I make sure to use my stir stick to get into the mix.

 

[egnald]

I've had Alumilite Clear Slow foam up when it cured without being under pressure, bubbles were trapped as it thickened and cured so not only did it look white because of the bubbles, it was thicker (height - not viscosity) because of the trapped air. - Dave

 

[JohnU]

Everything posted above needs to be given attention… correct amounts, mixed properly, but resin not under pressure is subjected to humidity moisture in the air, along with the bubbles from mixing and being created as it cures. It's not uncommon for unpressurized left over resin to bubble up and turn foamy white from air moisture. Just make sure you have equal amounts and mixed well when casting and you'll do just fine.

 

[RGABEL]

Thanks guys, I will do a smaller run of my clear casts to see how it turns out. The odd thing is I did a pour the day before using the same amounts but from a different batch of resin (was the end of that batch). When the unused potion cured it was basically clear (except for all the bubbles from mixing). Maybe it was a little more humid in my pouring area when I did this most recent pour. I am not good on documenting the ambient temperature and humidity when pouring. I guess I need to attend John's casting seminar at MWPTG again this year.

 

[its_virgil]

Curing white: Incorrect ratio or incomplete mixing. Kenny explained it well.
Foam: Caused by moisture. John U explained that well.
Pressure is REQUIRED because the chemistry of Alumilite Clear and Clear Slow (urethane resins) produces carbon dioxide as a byproduct. Pressure will keep the CO2 in solution so they are not visible. Without the pressure the CO2 will cause lots and lots of champagne bubbles and moisture in the air can compound the cast with foam.
Do a good turn daily!
Don