Pock Marked PR

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vtgaryw

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So, I just did some miniature pine cones in PR. One set was in a Maneater HDPE mold. The other was in a silicone mold. Both from the same can of PR. Mixed one right after the other, same mix ratios. In the same load in the pressure pot.

The ones in the Maneater mold (Green) came out perfectly smooth on all three sides. The ones in the silicone mold (Dark Red) came out pock marked on all three sides.

The only other difference between the two was the green blanks were mixed with a dash of Pearl Ex white and Emerald Green Mica powder. The dark red were mixed with a dash of Pearl Ex and Douglass and Sturgess Burgundy dye.

Any ideas what the cause of this is?

Txs,

Gary
 

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EBorraga

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Needed more pr in the red one. PR shrinks, so it creeps into cracks and crevices under pressure. I mix the pr and fill the mold immediately. This gives you 10-12 minutes for it to seep into the voids. You can then add more pr from the same mix before you put under pressure
 

Chasper

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I looks like the red blanks may have started to gel at the time they were poured and the green blanks were not yet at the gel stage when poured. Why would one gel quicker than the other?
1. You added the MEKP first, then separated the resin into two containers and mixed in the colors. Your poured the green first and the elapsed time between catalyzing and pouring was longer for the red.
2. You added an extra drop or two of MEKP with the red
3. You poured on different days or different time of the same day and the temperature was warmer when you poured the red

If none of the above happened, then as a next step I think I would mix enough resin for a two blank pour and pour it clear into the two molds within seconds of each other. Do they both reach the gel stage at the same time? If they do, then mix and pour the colors in two molds at the same time, do they gel at the same time?
 

vtgaryw

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Needed more pr in the red one. PR shrinks, so it creeps into cracks and crevices under pressure. I mix the pr and fill the mold immediately. This gives you 10-12 minutes for it to seep into the voids. You can then add more pr from the same mix before you put under pressure
Makes sense that it needed more PR, but why didn't the same thing happen with the green ones? Identical pine cones, same resin.

-gary
 

vtgaryw

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I looks like the red blanks may have started to gel at the time they were poured and the green blanks were not yet at the gel stage when poured. Why would one gel quicker than the other?
1. You added the MEKP first, then separated the resin into two containers and mixed in the colors. Your poured the green first and the elapsed time between catalyzing and pouring was longer for the red.
2. You added an extra drop or two of MEKP with the red
3. You poured on different days or different time of the same day and the temperature was warmer when you poured the red

If none of the above happened, then as a next step I think I would mix enough resin for a two blank pour and pour it clear into the two molds within seconds of each other. Do they both reach the gel stage at the same time? If they do, then mix and pour the colors in two molds at the same time, do they gel at the same time?
Definitely wasn't 1 or 3. 2 is possible. If I did, maybe it thickened too quickly and didn't get into all the nooks and crannies?

My other question is what about dyes? Do different types of dyes cause PR to react/set up differently?

-gary
 

ed4copies

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Yes to the dye question!! When Dawn poured PR (a decade ago), red could sit overnight and still be liquid in the morning.


Black set before we were finished pouring it.
 

Terredax

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My other question is what about dyes? Do different types of dyes cause PR to react/set up differently?

-gary
Absolutely. Colorants can have a drastic effect on resin. The colorants can have different chemical make-ups, and react to the resin.
I usually test new colorants in a small batch to test for reactions.
I actually had a manufacturer that I purchased from, and had some reactions. I let them know, and the director of marketing that I always dealt with, sent me their entire library of colors to test and report back. There were over 200 colors I tested.

Another thing I've had happen, is I believe with the silicone molds, static can build up, and that causes a surface tension that keeps the resin from adhering to the mold. I'm sure it was surface tension but, the static is a guess. When I use the silicone molds, I wipe them with a dryer sheet, and haven't had an issue since.

I prefer plastic molds.
 

vtgaryw

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Yes to the dye question!! When Dawn poured PR (a decade ago), red could sit overnight and still be liquid in the morning.


Black set before we were finished pouring it.
The red definitely was not as set up as the green, but I'm note sure how that explains the pock marks?

-gary
 

vtgaryw

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My other question is what about dyes? Do different types of dyes cause PR to react/set up differently?

-gary
Absolutely. Colorants can have a drastic effect on resin. The colorants can have different chemical make-ups, and react to the resin.
I usually test new colorants in a small batch to test for reactions.
I actually had a manufacturer that I purchased from, and had some reactions. I let them know, and the director of marketing that I always dealt with, sent me their entire library of colors to test and report back. There were over 200 colors I tested.

Another thing I've had happen, is I believe with the silicone molds, static can build up, and that causes a surface tension that keeps the resin from adhering to the mold. I'm sure it was surface tension but, the static is a guess. When I use the silicone molds, I wipe them with a dryer sheet, and haven't had an issue since.

I prefer plastic molds.
Interesting. I don't normally use silicone molds in the pressure pot, but then again I haven't normally been using pressure with PR, this was sort of a test to see how it did with the pine cones. I'll try that with the silicone mold next time.

So, what dyes can I use with what resins?

-gary
 

Terredax

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I would try wiping the mold, and use the exact colorants and resin, with the pine cones, just to eliminate the cause being the mold.
I would, at the same time, use the same mix and place it in your other mold. That would eliminate the colorant as the culprit.
 

vtgaryw

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Milton, VT
I would try wiping the mold, and use the exact colorants and resin, with the pine cones, just to eliminate the cause being the mold.
I would, at the same time, use the same mix and place it in your other mold. That would eliminate the colorant as the culprit.
Ah! The scientific method! I like it!

-gary
 

MRDucks2

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I learned that Silmar 41 and Alumilite Liquid dyes do not play well together. I thought it was odd I was not getting a heat change or gel as Ernie had showed me. It did set up and machine fine, after 4-5 days. Jay (tattooedturner) helped me ID the issue.


Sent from my iPhone using Penturners.org mobile app
 

vtgaryw

Member
Joined
Jul 24, 2012
Messages
610
Location
Milton, VT
I learned that Silmar 41 and Alumilite Liquid dyes do not play well together. I thought it was odd I was not getting a heat change or gel as Ernie had showed me. It did set up and machine fine, after 4-5 days. Jay (tattooedturner) helped me ID the issue.


Sent from my iPhone using Penturners.org mobile app
Yeah, I made that mistake once. This time, though, I made sure I used a PR dye.

-gary
 
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