Casting First casting attempt, no pressure pot, Alumilite Deep Pour, colours all blended together

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aldjmc

aldjmc

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Apr 3, 2017
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Moose Jaw, Saskatchewan, Canada
Hello experts,

Last week we made our first attempt at casting some blanks using Alumilite Deep Pour (2:1 by volume mix) without a pressure pot. The outside temperature was a wicked -48 Celsius but the shop was toasty at 18 degrees ( that's roughly -50 F outside and 65F inside). We mixed everything according to directions, poured the well stirred epoxy into smaller cups and then added some Micah powders for colours, and stirred some more. We poured a couple of colours into the molds and had some fun. Then, we left them for a week to cure. We popped them out of the molds tonight, and it looks like some of the powder settled to the bottom of the casting, and the colours mainly blended to make brown…what do I need to do differently?
I'm sure this has been asked and answered here before, but I couldn't find it. Any insight is appreciated.
 
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Color blending like that is due to the resin not setting when pouring. One way to avoid the colors blending is to wait a few minutes for the resin to set a little bit before pouring them together. This prevents color blending because the resin is thickening up. Don't wait too long for the resin as the longer you wait the less it will mix together at all.

Know the set times for the resin your using and have a plan but don't rush or drag it out too long. Spend a little extra time mixing the mica in the resin to help break up some of those "clots" to get a more even mixing of color.
 
I'll agree with Sabertooth on the temperatures. The Deep Pour Resin takes 3 days to set so I can demold. They said a week to cure. I think you need something that has a shorter set time. I'm not sure if there's a sweet spot between color separation and bubble free without a pressure pot.
 
Not familiar with alumilite deep pour. I would wait to mix the colors together until the resin starts to warm up a bit before pouring. I've used slower curing resins and have waited up to an hour after mixing to pour into a mold. I made a pressure pot for casting out of a piece of metal pipe, a cap, and a bunch of reducers to get it down to where I could put an air fitting on it. I would just leave it hooked to the compressor to keep it pressurized.
 
I would avoid deep pour resins for pen blanks. I didn't know anything about resins when I first started using them, and the only stuff I could find locally was some deep pour. Every time, I got blended colors, because the deep pour stuff is intended for an entirely different purpose (deep pours 1-2 inches thick for each layer, which is most often used for things like resin tables and the like). The deep pour resins take a long time to set, and if you follow the instructions to keep the resins warm while they cure, then they are also fairly fluid, so any separation of colors you start out with will inevitably be blended together by the time the resin sets (which is often measured in tens of hours to days). Deep pour resins can take weeks to cure.

For pen blanks, you want resins that set and cure much faster. It took a while (this was back in 2020 when I first started) before some Alumilite Clear finally returned to my local stores. I started with the 7 minute stuff, and had problems with bubbles, as I could never really get the resins mixed properly, dyed thoroughly, poured, lightly mixed to create the swirls I wanted, in the pressure pot and finally up to the necessary 40 PSI before things had hardened and frozen the bubbles in place (i.e. unable to be crushed properly by the pressure).

I have been using Alumilite Clear Slow, which has a 12 minute open time. This has improved my ability to properly mix, pour, swirl and get things pressurized. I have found that you need to wait until just the right time to try and start swirling different colors in a blank. Too early, and they can still blend together...too late, and you won't be able to get the blanks in the pot before the bubbles harden and can't be crushed. Some people use a temperature gauge, and don't start trying to blend multiple colors together until the temp reaches around 125-150 degrees...I haven't yet picked up one of those IR thermometers to do that.

I have also started mixing my pigments into my resins before I mix in the hardener. This gives me all the time I could need to get colors right, without having to worry about open time. Once I get my colors right, I then mix in the hardener, which gives me most of the 12 minutes to get things poured and swirled and under pressure. The 12 minute Clear Slow urethane resin is usually set in 4 hours, and cured within a day.
 
aldjmc said:
Hello experts,

Last week we made our first attempt at casting some blanks using Alumilite Deep Pour (2:1 by volume mix) without a pressure pot. The outside temperature was a wicked -48 Celsius but the shop was toasty at 18 degrees ( that's roughly -50 F outside and 65F inside). We mixed everything according to directions, poured the well stirred epoxy into smaller cups and then added some Micah powders for colours, and stirred some more. We poured a couple of colours into the molds and had some fun. Then, we left them for a week to cure. We popped them out of the molds tonight, and it looks like some of the powder settled to the bottom of the casting, and the colours mainly blended to make brown…what do I need to do differently?
I'm sure this has been asked and answered here before, but I couldn't find it. Any insight is appreciated.
Click to expand...

The deep pours are not ideal for blank casting and probably should be avoided. Some epoxies are fine like JB Royal or the various Alumilite casting resins designed for the small turning casts. These types are engineered specifically for this purpose and have much shorter set times.
 
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