Alumilite Clear Slow Open Time

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KMCloonan

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Jun 13, 2017
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Hi - I looked through this forum, but did not find an answer to this question. I hope some of the experienced resin casters can provide some guidance. I am starting to cast, using Alumilite Clear Slow resin, which has a stated "open time" of 12 minutes at 75 degrees F. I have also been watching some videos by Zac Higgins, Jake Thompson, etc who suggest waiting to pour/mix/swirl colors until your resin is at 95 degrees F.

Yesterday, I started a resin pour - I mixed a small batch, then divided it into 3 cups, for 3 different colors. This part of the process took me 6 minutes. I forgot to mention, my basement shop is pretty cool this time of year. It barely cracks 60F.

Anyway, I mixed the 3 resin cups, and kept checking the temperature. At 11 minutes of open time, the resin was at between 75 and 80 degrees. I decided to go ahead, pour and get the mold in the pressure pot, which I was able to do by the 13 minute mark.

So my question is: If I am starting at a cooler temperature, do I have more open time? Which is more important, the 12 minute open time, or the 95 degree pouring?

Thanks for any help!

By the way, the blanks turned out pretty well, but I would have liked a little more color separation.
 

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JohnU

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The working time is usually an average set by the manufacturer. The temp is what's important. I usually use " Clear" with a 7 min working time because I don't like waiting so long for my resin to hit 110 degrees in color pours. Slow is great for deeper, larger pours, because it's slow cure helps cut back on the risk of thermal cracking. It's great when starting out giving you extra time to learn your process. For better color separation, start your pour around 110 -112 degrees, unless you use alumilite white, then start around 95 -100 because it cures much quicker. By the way… your blanks look good!
 

KMCloonan

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Joined
Jun 13, 2017
Messages
1,502
Location
Round Lake, Illinois
The working time is usually an average set by the manufacturer. The temp is what's important. I usually use " Clear" with a 7 min working time because I don't like waiting so long for my resin to hit 110 degrees in color pours. Slow is great for deeper, larger pours, because it's slow cure helps cut back on the risk of thermal cracking. It's great when starting out giving you extra time to learn your process. For better color separation, start your pour around 110 -112 degrees, unless you use alumilite white, then start around 95 -100 because it cures much quicker. By the way… your blanks look good!
Thanks John! I really appreciate the advice.

Thanks also for the kind comment about my blanks. I am pretty happy with my first attempt.
 

JohnU

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Jan 31, 2008
Messages
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Location
Ottawa, Illinois
Here's a pen made with my first cast resin. Diamond Knurl Gun Metal & Chrome.
That's the fun part of casting…. You never know what character you get inside a blank until you turn it. I've seen many casts that have a bland outside that come to life inside. Congrats ! My first never had anything close to the character you have in yours. Keep up the great work!
 
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