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Casting resin and my problems with nightglow pigments


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Old 10-16-2016, 09:38 PM   #1
Knallfrosch
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Default Casting resin and my problems with nightglow pigments

I like to experiment with new materials, colors and such.
I am using casting resin for a while now making my own paper micarta
and various colored sheets to be used as scales for slingshots of course.

At first i made a square casting form to make sheets and cut out the slingshot designs as usual boardcut.

But in the longrun that was quite expensive because of the cut offs that
cannot be used further and not all colors are nice enough to use them on a slingshot.

With my blossom design my wish for more colors and experiments with
casting resin grew stronger and i decided to make a silicone mold to cast
a slingshot scale without the need of cutting it out of a full sheet.
On the first picture you see the silicone mold made from my master-template.
It only takes ~20ml instead of over 300 for a full sheet.

So far so good.

Color pigments usually mix perfectly with the resin forming a homogenous
suspension resulting in a completely colored cast.
But for some reason, nightglow pigments don´t behave like that.

On my fist try with nightglow pigments i only got a thin layer of those on the bottom of the sheet.
Next two tries i used different thixotropic powders to make the solution thicker
( one was recommended by the resin manufacturer for my problem )
but it still doesn´t work. As you can see on the next pictures,
the nightglow pigments still settle on the bottom of the casting mold
and do not stay in solution.
My goal is to imitate the nightglowing kirinite sheets that i recently bought.

My last try with a 15 ml amount of resin i used a half tablespoon of
nightglow powder and a teaspoon of the thixotropic powder and stirred for 20 minutes...
it takes that long to make the pigments dissolve properly.

My guess is, these pigments are heavier than normal color pigments.
But there must be some way to keep them floating.
If someone have any idea how to solve this, i would be happy.

Thanks.


Attached Images
File Type: jpg Mold.jpg (23.4 KB, 41 views)
File Type: jpg Cast downside.jpg (9.0 KB, 40 views)
File Type: jpg Cast upside.jpg (7.7 KB, 42 views)
File Type: jpg Cast side.jpg (8.9 KB, 40 views)
File Type: jpg Cast side2.jpg (9.9 KB, 43 views)
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Old 10-17-2016, 12:02 AM   #2
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Thanks for all the information.


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Old 10-17-2016, 01:31 AM   #3
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I seem to remember from somewhere/when of another builder having the same issue. I want to say that he mounted the form to a low rev shaft. (A rotisserie?) and the particles never had the chance to settle into a layer. I can't swear to this though.
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Old 10-17-2016, 02:32 AM   #4
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Quote:
Originally Posted by Flipgun View Post
I seem to remember from somewhere/when of another builder having the same issue. I want to say that he mounted the form to a low rev shaft. (A rotisserie?) and the particles never had the chance to settle into a layer. I can't swear to this though.
Hmm.
Well thanks, i have to check, if i can do that with my equipment.
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Old 10-17-2016, 05:56 AM   #5
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Nice information i like that you are trying different things for home building
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Old 10-17-2016, 02:04 PM   #6
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Apparently i was to hesitant with the thixotropic powder.
I tried another one with a lot of that stuff in it until the resin had the texture of thick toothpaste.
I had to smear it into all the edges... but the result was encouraging.

Also i found some more tutorials and they mostly use resin that cures within a couple of minutes, so that the
pigments don´t have the chance to settle. I tried to compensate that with my 40-minutes-open-time-resin and put it in the oven for 45 minutes at ~50°C/122°F
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Old 01-11-2017, 05:18 PM   #7
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It seems that the "open time" of the casting resin is the key to a successful cast.
I tried a different resin with an open time of 10 minutes instead of 40 mins.
And voilà a completely glowing piece of resin .
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File Type: jpg new glow cast.jpg (9.2 KB, 16 views)
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Old 01-11-2017, 11:21 PM   #8
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Nice
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Old 01-12-2017, 01:17 AM   #9
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Very nice, I just got 10 buckets of silicone mold material and was wondering what to do with it. Do you have to degas the resin when you make it?
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Old 01-12-2017, 09:13 AM   #10
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If you have a vacuum chamber, it is definitely better if you do.
I don´t have a vacuum chamber, though.
I have to sand away the cavities from bubbles at the surface, or fill them with clear resin.
You can pop bubbles with a lighter flame as long as the resin is still liquid,
but i often have tiny bubbles that tried to espace afterwards and just made it to the surface and
were trapped there.


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