Ted iin Michigan
Member
I'm going to give in and (finally) do some casting. Would really appreciate your recommendations on which resin(s) a new caster might start out with.
Thanks in advance,
Thanks in advance,
Resin recommendation
- Thread starter Ted iin Michigan
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Jim_V
Member
Always had good results with Silmar 41 from http://www.uscomposites.com/polyesters.html
MRDucks2
Member
You may want to think about two things and then ask:
- what/how are you wanting to cast to start out? Embed items and make hybrids colorful blanks.
- what parameters are important to you. Cast under pressure or not? How big of a deal is smell. How about time; do you want to cast and turn in the same day, is waiting a few days OK? Are very durable blanks important.
All of this will have an impact on the best answers for you.
- what/how are you wanting to cast to start out? Embed items and make hybrids colorful blanks.
- what parameters are important to you. Cast under pressure or not? How big of a deal is smell. How about time; do you want to cast and turn in the same day, is waiting a few days OK? Are very durable blanks important.
All of this will have an impact on the best answers for you.
jttheclockman
Member
I agree with the Duckman. Those are important question not only for final results but for needs too. I believe all resin respond better under pressure so I recommend it. Epoxy resin a re the new kid on the block compared to all others and they work well when doing cast on tubes because they stick to everything and do not pull away when curing. So there is no one answer to your question.
Ted iin Michigan
Member
Thanks, folks.
MRDucks2 - Casting under pressure. I've been doing mostly wood pens lately but really want to try the "worthless wood" style. My shop is in an outbuilding so smell is not a totally bad thing. Time is not a major consideration.
I'm thinking of starting with Alumilite clear. Thoughts?
MRDucks2 - Casting under pressure. I've been doing mostly wood pens lately but really want to try the "worthless wood" style. My shop is in an outbuilding so smell is not a totally bad thing. Time is not a major consideration.
I'm thinking of starting with Alumilite clear. Thoughts?
jttheclockman
Member
My opinion starting with Silmar is the better choice. Less chance of not getting mix ratios right. With silmar it is just a matter of adding drops of catalyst and no particular set amount except that use over 6 drops per ounce you start getting into the brittle stage of a blank. I use 4 drops. You said worthless wood then Alumilite would be better. Good luck.
1080Wayne
Member
Definitely Alumilite clear for worthless wood . Just make sure it is very dry (<6% MC)
MRDucks2
Member
Alumilite Clear or Clear Slow for the hybrids. Liquid Diamonds would also likely work for the Hybrids and works as well as Alumilite with embedded objects.
Silmar 41 does not work well with embedded objects or hybrids as it's shrinkage is greater and it can pull away from your wood in addition to the sides of the molds.
Both Silmar 41 and Alumilite can be cast and turned in the same 24 hour period following standard practices.
Liquid Diamonds needs some time to fully cure. It can be mixed harder so you only need 2-3 days to cure. Standard practices for me in Indiana required 7 days before I could turn it.
I have never had an issue with ratios on Alumilite. Oddly, I have had more problems with getting Silmar 41 to do what I wanted.
I did have an issues with Alumilite not getting mixed thoroughly enough when I was adding pigment before mixing. I now mix until it turns clear again then add my pigment and have done well.
As John pointed out, while only Alumilite Clear requires pressure due to it's higher viscosity, all do better under pressure.
Silmar 41 does not work well with embedded objects or hybrids as it's shrinkage is greater and it can pull away from your wood in addition to the sides of the molds.
Both Silmar 41 and Alumilite can be cast and turned in the same 24 hour period following standard practices.
Liquid Diamonds needs some time to fully cure. It can be mixed harder so you only need 2-3 days to cure. Standard practices for me in Indiana required 7 days before I could turn it.
I have never had an issue with ratios on Alumilite. Oddly, I have had more problems with getting Silmar 41 to do what I wanted.
I did have an issues with Alumilite not getting mixed thoroughly enough when I was adding pigment before mixing. I now mix until it turns clear again then add my pigment and have done well.
As John pointed out, while only Alumilite Clear requires pressure due to it's higher viscosity, all do better under pressure.
Ted iin Michigan
Member
Wow, lots of great stuff. Thanks, all!!
But yet one more Q - I'm making my molds out of UHMW PE. Do I need a release agent? If yes, what would you recommend for Alumilite Clear?
Again, thanks in advance.
But yet one more Q - I'm making my molds out of UHMW PE. Do I need a release agent? If yes, what would you recommend for Alumilite Clear?
Again, thanks in advance.
jttheclockman
Member
Ted iin Michigan
Member
Thanks, JT!
TattooedTurner
Member
Alumilite - easiest to turn but doesn't polish as well and is expensive. It will shine, but it lacks the "depth of shine" you get with the other 2.
Epoxy - great polish, not as easy to turn as Alumilite but not bad, costs more than Silmar 41. Has a longer curing/thickening time which can be a problem if you want a stark border between colors.
Silmar 41 (polyester resin) - cheaper than the others, polishes as good as epoxy but can be brittle. If you cast in round pvc molds the brittleness isn't much of an issue, it's rounding out square blanks where it's a problem. Not recommended for casting below 60 degrees, I prefer above 70.
Hope this helps. I've used and prefer Silmar 41 from the start, but most of the time I cast round molds. Alumilite just doesn't finish as well so I only use it if I need to cast in cold temps which is rare as I keep a lot of blanks (75+ ) on hand. I like that Silmar thickens much faster than epoxy so I can keep the colors separate but still get a good mix/swirl in 10 minutes instead of waiting an hour.
As for curing, recently I read that Alumilite takes 7 days at room temp to fully cure. I give Silmar 2 weeks minimum. Demold time isn't the same as curing time. In my experience a fully cured blank will polish to a deeper shine than one that isn't.
Epoxy - great polish, not as easy to turn as Alumilite but not bad, costs more than Silmar 41. Has a longer curing/thickening time which can be a problem if you want a stark border between colors.
Silmar 41 (polyester resin) - cheaper than the others, polishes as good as epoxy but can be brittle. If you cast in round pvc molds the brittleness isn't much of an issue, it's rounding out square blanks where it's a problem. Not recommended for casting below 60 degrees, I prefer above 70.
Hope this helps. I've used and prefer Silmar 41 from the start, but most of the time I cast round molds. Alumilite just doesn't finish as well so I only use it if I need to cast in cold temps which is rare as I keep a lot of blanks (75+ ) on hand. I like that Silmar thickens much faster than epoxy so I can keep the colors separate but still get a good mix/swirl in 10 minutes instead of waiting an hour.
As for curing, recently I read that Alumilite takes 7 days at room temp to fully cure. I give Silmar 2 weeks minimum. Demold time isn't the same as curing time. In my experience a fully cured blank will polish to a deeper shine than one that isn't.
Ted iin Michigan
Member
Thanks, Jay. Great info. It's going to be a new adventure!
Don Rabchenuk
Member
Alumilite clear slow for casting "worthless wood" as it gives you a bit more time than Alumilite clear.
TattooedTurner
Member
Yes it is! I enjoy casting blanks almost as much as turning them. There's nothing like having one turn out far cooler than you expected, knowing it was your hand that created it.