Recommendations On A Non-Allergic Casting Resin

[oldcarfan]

I cast resin parts occasionally but last month I bought a casting kit from Hobby Lobby which is what I've used before, and seem to have had problems. I cast and sand the parts using protection, a mask, avoid dust, etc. and never noticed any issues before, but this time it seems to have caused an allergic reaction. My nose got stuffy within a half hour and I felt like I had a cold for several days.

The question, I guess, is there any other type of easily gotten resin that isn't the standard Alumalite type? I don't use enough to buy a large quantity.

Any tips appreciated.

[gman]

Sensitivity to resins might not start off with an allergic reaction, but it can end up that way with cumulative exposures. While formulas often differ, you might have to try a few different brands depending on what you can find in small quantities...you don't want to commit to a gallon or more if it ends up causing the same reaction.

I went through quite a bit of Por-A-Kast one year, and while my symptoms weren't horrible they seemed to intensify after several months of use and would be less once the resin had fully cured. The Por-A-Kast worked pretty well but was pretty smelly. Hobby Lobby shows Amazing Casting Resin (white) available if that is what you are using. If you plan to buy online, there are a number of other suppliers- you might get some good recommendations from the regular casters on the forum.

[NOBLNG]

I use Smooth-On products with great results. I don’t know if they are more non-allergenic?

[gman]

Smooth-On was going to be the next product I'll try when I gear up to cast some more parts. There is a distributor for their products close to me. Availability had a lot to do with the last product I tried, as a local brick & mortar hobby shop stocked it. Thankfully there are online sources for many different resins these days.

[Ace-Garageguy]

39 minutes ago, gman said:

Thankfully there are online sources for many different resins these days.

I have used casting materials from both of these companies extensively and never had any allergic issues.

This is no guarantee, but as both of them are sellers to professionals and industry, their customer service may be able to help you.

https://www.freemansupply.com/

https://polytek.com/

[robdebie]

20 hours ago, oldcarfan said:

I cast resin parts occasionally but last month I bought a casting kit from Hobby Lobby which is what I've used before, and seem to have had problems. I cast and sand the parts using protection, a mask, avoid dust, etc. and never noticed any issues before, but this time it seems to have caused an allergic reaction. My nose got stuffy within a half hour and I felt like I had a cold for several days.

The question, I guess, is there any other type of easily gotten resin that isn't the standard Alumalite type? I don't use enough to buy a large quantity.

It might be difficult to answer, but does the allergic reaction develop during the casting, or the sanding of the resin? If you know the answer, you can focus on improving your safety measures on that phase.

Judging from the whole sheet of safety warnings on one of the components of the Smooth-On resin that I use, the casting operation is not without risk. The dangers of isocyanates are not to be underestimated. I know one Dutch seller who stopped PU resin sales, he couldn't take the responsibiliy anymore.

Judging from modelers' stories, the sanding phase gives most problems, usually in the shape of nose bleeds that won't stop.

Rob

[oldcarfan]

Definitely in the sanding process. Maybe its just built up over time and finally hit a noticeable level.

[Fat Brian]

1 hour ago, oldcarfan said:

Definitely in the sanding process. Maybe its just built up over time and finally hit a noticeable level.

I wonder if wet sanding would help? That should keep he dust to about zero.

[oldcarfan]

6 minutes ago, Fat Brian said:

I wonder if wet sanding would help? That should keep he dust to about zero.

That's a good suggestion, I'll have to try it.

[Ace-Garageguy]

33 minutes ago, oldcarfan said:

That's a good suggestion, I'll have to try it.

I don't know what kind of mask you're using, but dust masks are next to useless in my experience.

I won't sand any composite or catalyzed material without something like this at the minimum:

                                            

Edited January 28 by Ace-Garageguy

[OldNYJim]

@oldcarfan, which product were you using - was it this one?

Not at ALL helpful for your question, but I was curious how well you liked it…I was planning on doing some more casting here soon and didn’t really Hobby Lobby actually carried this…

[oldcarfan]

19 hours ago, CabDriver said:

@oldcarfan, which product were you using - was it this one?

Not at ALL helpful for your question, but I was curious how well you liked it…I was planning on doing some more casting here soon and didn’t really Hobby Lobby actually carried this…

That's the one!

[OldNYJim]

4 hours ago, oldcarfan said:

That's the one!

Thank you!  Picked some up this evening…didn’t realize they sold this

[Casey]

On 1/28/2025 at 10:47 PM, CabDriver said:

Not at ALL helpful for your question, but I was curious how well you liked it…I was planning on doing some more casting here soon and didn’t really Hobby Lobby actually carried this…

https://www.modelcarsmag.com/forums/topic/178677-alumilite-alumires-resin-casting-kits-no-longer-at-hobby-lobby/

[Casey]

Just FYI, the Alumilite Casting Resin is a very poor choice for beginners. It leaves you very little time for proper mixing and sets very quickly-- both not ideal when you are still trying to get the hang of it. Get something with a longer pot life and slower cure time.

Buy yourself an accurate scale which reads in grams, a good plastic measuring cup or two with a pour spout, and toss out anything porous you might use to mix the two parts together-- the less air you introduce the better. If you are meticulous and have great close-up vision, you should be able to make small parts without deep undercuts in one-part molds without a vacuum de-gassing your mold rubber first. It works, but you will likely quickly see the benefits or properly de-gassed mold rubber, as well as the benefits of using a pressure chamber when casting the parts.

[oldcarfan]

On 1/28/2025 at 10:47 PM, CabDriver said:

@oldcarfan, which product were you using - was it this one?

Not at ALL helpful for your question, but I was curious how well you liked it…I was planning on doing some more casting here soon and didn’t really Hobby Lobby actually carried this…

I like it, it comes in just the right amounts for the castings I do and the price seems decent. I've used it before and never had an problems.

[OldNYJim]

11 hours ago, Casey said:

Just FYI, the Alumilite Casting Resin is a very poor choice for beginners. It leaves you very little time for proper mixing and sets very quickly-- both not ideal when you are still trying to get the hang of it. Get something with a longer pot life and slower cure time.

Buy yourself an accurate scale which reads in grams, a good plastic measuring cup or two with a pour spout, and toss out anything porous you might use to mix the two parts together-- the less air you introduce the better. If you are meticulous and have great close-up vision, you should be able to make small parts without deep undercuts in one-part molds without a vacuum de-gassing your mold rubber first. It works, but you will likely quickly see the benefits or properly de-gassed mold rubber, as well as the benefits of using a pressure chamber when casting the parts.

Good tips, thank you!  I’ve done a decent amount of casting, but I’ve never got as far as investing in a pressure pot…