# Polyurathane or Polyester for casting?



## jhogan9600 (Feb 25, 2011)

I'm ready to try my had at casting and have looked and read quite a bit about it over the last few weeks. Should I go with polyurathane resin for polyester resin? I understand polyester is a bit softer and it's cheaper than polyurathane. Are there any other differences? I've had lots of trouble lately with my purchased blanks being too transparent... so the ability to hold lots of color is important to me. 
Thanks!


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## micharms (Feb 25, 2011)

John:
If you check lots of the posts most people are painting the insides of the blanks and/or the tubes before gluing to solve the transparency problem. It seems that painting the blanks is better to hide glue lines. I'm not speaking from personal experience justnwhat I have read here on IAP.

Michael


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## DozerMite (Feb 25, 2011)

It's a matter of preferrence and what it will be used for.
The urethanes are more technical and less open time. They do not like water, it causes foaming.
PR is less technical and open time can vary depending on many factors. It will tolerate water based paints if you choose to use that for a colorant. I've had water leak into the container when warming in a bath. The water just floats to the top.
As for translucency, when casting, it will also depend on several factors. I occasionally still get some translucency in spots, but not often. I do paint the blanks irregardless. Always best to be safe.

If you do decide to cast...

Make sure to read the MSDS on the materials you use and understand ALL of the DANGERS. Not just the resins, but the pigments, dyes, catalyst, etc. all pose some level of toxin risk.
Most people don't fully research casting and if the materials are mishandled and the proper precautions not followed, there will be a price...... 

Is your health... or even your life... worth taking shortcuts??

Cast SAFE!


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## animefan (Feb 25, 2011)

My suggestion for casting would have to be silmar 41 it makes a great acrylic blank if cast right. As far as the translucency problem you might want to consider painting your tubes or adding pigment to your epoxy mixture.


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## its_virgil (Mar 4, 2011)

Both have their place in what we do. For clear casting embedded material such as ssnake skin and computer printed labels polyester resin is the better choice. For making coffee bean blanks and other similar blanks and the worthless wood blanks that Curtis makes then alumilite is the better choice. Polyeester resin does well for dyed or colored blanks as does alumilite. Polyester resin polishes a bit more shinnier but is also a bit more brittle than alumilite. I've had polyester resin blanks crack if dropped onto a concrete floor but I can't remember having one crack made from alumilite. Both are excellent and both have good and not so good qualities.
Do a good turn daily!
Don



jhogan9600 said:


> I'm ready to try my had at casting and have looked and read quite a bit about it over the last few weeks. Should I go with polyurathane resin for polyester resin? I understand polyester is a bit softer and it's cheaper than polyurathane. Are there any other differences? I've had lots of trouble lately with my purchased blanks being too transparent... so the ability to hold lots of color is important to me.
> Thanks!


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## MesquiteMan (Mar 5, 2011)

its_virgil said:


> Both have their place in what we do. For clear casting embedded material such as ssnake skin and computer printed labels polyester resin is the better choice. For making coffee bean blanks and other similar blanks and the worthless wood blanks that Curtis makes then alumilite is the better choice. Polyeester resin does well for dyed or colored blanks as does alumilite. Polyester resin polishes a bit more shinnier but is also a bit more brittle than alumilite. I've had polyester resin blanks crack if dropped onto a concrete floor but I can't remember having one crack made from alumilite. Both are excellent and both have good and not so good qualities.
> Do a good turn daily!
> Don
> 
> ...



Don, old buddy, you are softening up in your old age!!!  I remember when you and I used to battle (in fun of course) over which was better!


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