Poly resin difference?

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Paul Downes

Member
Joined
May 19, 2004
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216
Location
Westphalia, Mi, USA.
I have used 2 different brands of poly resin. 1 gallon from artstuff and 2 gl. of simlar41 from us composites. I have had some cracking problems with the simlar41. I dropped one pen section and it cracked in 2 places. I also have had some end cracks either from drilling or end milling. I'm not sure if the problem is because I have started using a gelling agent ar if it's the simlar41. I generally use the same amount of hardener/activator. There is a difference between the 2 resins, at least in color. The artstuff resin looks pretty clear, the simlar41 has a slight blue color to it so assume the recipe is different. What do you folks think?
 
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I use the Simlar 41 from Mr. Fiberglass and never had cracking issues. Mine isn't blue either, it's crystal clear.
It will get a little brittle if you use more than 10 drops of MEKP per ounce so that's something to consider. I don't have any idea what gelling agent does as far as cracks go but why are you using it anyway, I thought it was for skim coats and cold weather?
 
Paul Downes said:
There is a difference between the 2 resins, at least in color. The artstuff resin looks pretty clear, the simlar41 has a slight blue color to it so assume the recipe is different. What do you folks think?
Click to expand...

Once you pour your Silmar 41 into your main mixing dispensing cup let the bubbles rise out and you will notice a color flash typically from slight yellow to bluish.

If it is already comming out of your dispensing can bluish, then you are not closing the lid tighlty after use, or your resin has aged a little.
 
It was faintly blue when I opened it the first time. Maybe I got an old can? I do put the lid back on tight so I don't think that is the issue. I will cut back on the hardener a bit. I was useing 9 drops per oz. maybe that is too close to the line on brittleness. I have been experimenting with the geling agent to attempt to get a certain mix of the colors. So far it hasn't worked as I hoped. I have come up with another idea and will try that as soon as I get an order from artstuff. I Won't need the geling agent with the new idea. If it works I will be posting a picture of the pen.
 
i use silmar 41 from u.s. composites and it has a very slight color tinge, i use 3 or 4 drops per oz, in this hot weather i use their colorants, both opaque and transparent, just a drop or two per oz. and i use pearl ex with the transparent dyes or by it's self, i'd bet the problem is the amount of either gel enhancer or hardener, when last i cast about 3 weeks ago the temp was around 90 to 95deg 60 humidity, and gel time was around 12 to 15 min, for pens and a bit longer on bottle stoppers, they had quite a bit more dye and pearl ex, even the thin mid layer and tops which were clear geled in under 10 min,
 
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