Updated - Resin Comparison

[vtgaryw]

I had taken an initial shot at this a couple of years ago but never really finalized it. But when Royal Palm went out of business (which had been my go-to epoxy for clear casting) I decided to do a little research since there were so many Alumilite formulations out there. So, here's my latest iteration. I only included resins for which I could find Manufacturer's Technical Data Sheets. Several of the Alumilites may not be useful for pen making, but their website was so comprehensive I threw them all on there.

I'm open to suggestions on other fields I could add, and links to any other resins people might be using (as long as I can find enough info on them.)

 

[Brandy]

That's super helpful! Thanks!

 

[Jim Campbell]

I was recently looking for something to fill a large crack on a wooden bowl I was turning. I visited Rockler. They are selling an epoxy brand called MAS. The one I purchased is MAS Penetrating Epoxy Sealer. This particular epoxy is designed for punky wood. They also sell a couple of other epoxy products under the MAS label.

The MAS Penetrating Epoxy Sealer has a 30 minute set time and is a low viscosity epoxy, much like Diamond.

It's a 2:1 mix with 2 parts resin and 1 part hardener. In reading the instructions it can be thinned using pretty much any petroleum based thinner, acetone, or denatured alcohol.

The one ding I have is it will blow through blue tape. I ended up using hot glue.

 

[its_virgil]

I had taken an initial shot at this a couple of years ago but never really finalized it. But when Royal Palm went out of business (which had been my go-to epoxy for clear casting) I decided to do a little research since there were so many Alumilite formulations out there. So, here's my latest iteration. I only included resins for which I could find Manufacturer's Technical Data Sheets. Several of the Alumilites may not be useful for pen making, but their website was so comprehensive I threw them all on there.

I'm open to suggestions on other fields I could add, and links to any other resins people might be using (as long as I can find enough info on them.)

Silmar 41 is a polyester resin not a polyurethane resin

 

[jttheclockman]

I can tell you Silmar is by far hardness is more than that. It is far harder than Liquid diamonds and I use both. In fact the more drops of catalyst the harder it will get and can become too brittle so care is needed.

 

[vtgaryw]

Silmar 41 is a polyester resin not a polyurethane resin

You know, I knew that, I think I started typing polyester and excel filled in polyurethane... Thanks.

 

[vtgaryw]

I can tell you Silmar is by far hardness is more than that. It is far harder than Liquid diamonds and I use both. In fact the more drops of catalyst the harder it will get and can become too brittle so care is needed.

The test method they use for hardness is more dent resistance. There's a lot of other mechanical properties listed in the TDS's that also affect the blank (tensile strengths, flex, etc.). I couldn't find an exact mapping of the Barcol tester to the Shore tester. They both press on the surface, but the tip geometry they use is different, so it's not an exact comparison. I know from doing a bunch of hybrid bowls and vases with Silmar that I have a way harder time getting scratches out of the Silmar than any epoxy I use.

 

[vtgaryw]

One thing I couldn't find much info on was which resins contain UV Protectants to minimize yellowing. Ironically, the one from Oakbrook that I didn't include in the chart because it didn't have a TDS says that it has a UV protectant. Anyone know if any of the standard resins do?

 

[its_virgil]

One thing I couldn't find much info on was which resins contain UV Protectants to minimize yellowing. Ironically, the one from Oakbrook that I didn't include in the chart because it didn't have a TDS says that it has a UV protectant. Anyone know if any of the standard resins do?

Never had a polyester resin blank cast clear to yellow. Every epoxy I have used to cast clear has yellowed.

 

[bmachin]

One thing I couldn't find much info on was which resins contain UV Protectants to minimize yellowing. Ironically, the one from Oakbrook that I didn't include in the chart because it didn't have a TDS says that it has a UV protectant. Anyone know if any of the standard resins do?

Here is what I am aware of:

There is an epoxy called ArtResin which uses HALS (I think) UV absorbers. It was brought to our attention several years ago. It is not designed as a turning resin, but rather as a coating resin. To the best of my knowledge only one person has turned a pen from it and was not particularly happy with the process. The company did an aging comparison video which is available online.

Liquid Diamonds, a local favorite, claims to be UV resistant but does not say how or why.

Alumilite Amazing Clear Cast Plus contains UV "absorbers" (actually free radical absorbers). Eventually though, those will be used up.

Alumilite has a very good video explaining the chemistry of epoxy yellowing here:

Bill

 

[jttheclockman]

I do not know what resins have UV or not but I will say years ago I bought a few of these fiberglass blanks and at that time I have no idea what they were cast in and still do not but can safely say it was not epoxy resins because at that time they were not even being talked about. Now weather it was Alumilite or Silmar or some other resin, they have been sitting in a box all this time. I happen to stumble upon them the other day just looking through some stuff. They are as yellow as can be so I would never say Silmar or alumilite or any other resin does not yellow. That would be false advertising. Now they say will not discolor or break down. The thing is we probably would never know because when we turn down a blank in any other resin, it is so thin and the subject matter behind it will mask any yellow coloring. This could be the case with the blanks I have linked too. Maybe someone has used them and can verify.

https://www.woodturnerscatalog.com/p/12/5061/artisan-Glass-Fiber-Pen-Blanks?c=331

 

[bmachin]

Don't know how important it might be but there is a property called Heat Deflection Temperature which is basically the temperature at which a casting can be dented bwill return to its original shape once the pressure is relieved.

Here is a link to an article from Alumilite explaining the concept as well something called temperature resistance. There is a video link in the article as well.

Heat Deflection Temperature vs. Temperature Resistance

TLDR: Heat deflection temp is the temperature at which epoxy get's slightly bouncy but returns to normal when cooled and Temperature Resistance is when epoxy becomes permanently damaged. *Short vid...

support.alumilite.com

Bill

 

[vtgaryw]

Don't know how important it might be but there is a property called Heat Deflection Temperature which is basically the temperature at which a casting can be dented bwill return to its original shape once the pressure is relieved.

Here is a link to an article from Alumilite explaining the concept as well something called temperature resistance. There is a video link in the article as well.

Heat Deflection Temperature vs. Temperature Resistance

TLDR: Heat deflection temp is the temperature at which epoxy get's slightly bouncy but returns to normal when cooled and Temperature Resistance is when epoxy becomes permanently damaged. *Short vid...

support.alumilite.com

Bill

I thought about including that in the chart, wasn't sure it would be very useful to most of us. For one thing, the temps were all pretty high, and if we got pen blanks up to that temp, even if it technically returned to its original shape, we would still have to fix the blank. ???

 

[vtgaryw]

Never had a polyester resin blank cast clear to yellow. Every epoxy I have used to cast clear has yellowed.

The Oakbrook Wood Turning Epoxy said it had a UV protectant in it, but I didn't see anything about it from either Alumilite or LD. I'm going back more and more to Silmar 41 after years of messing with epoxies.

 

[McKenzie Penworks]

Heat deflection is a pretty important property for machining. If you don't believe me, take some sandpaper to a blank on the lathe and use an IR thermometer to measure the heat. 100 degrees F is pretty low and is kind of the standard for the cheaper epoxy options. It also becomes important in a pen because your car will easily hit 130+F in the summer with the sun coming in. Leaving a pen in the car could result in disaster if it was made from an inexpensive resin with low heat deflection temps. Heck I know of a big name brand company that shipped a pen to someone in Arizona only to have it show up warped because of the heat encountered in the shipping process.

 

[its_virgil]

Liquid Diamonds...cast about 1yr ago. Has been in my desk drawer since cast. Has never been anywhere except in that drawer.
Do a good turn daily!
Don

 

[PatrickR]

I have some purchased abalone blanks cast in ?, stored in the dark for 3+ years and was surprised how yellow they are. Acrylic is the only clear plastic I'm aware of that does not yellow in time.


Sent from my iPad using Tapatalk

 

[McKenzie Penworks]

Acrylic certainly holds up the best. There are a few premium resins out there that do better at staying clear but they typically require some specialized heat curing, etc. The good news is that once you turn a blank down that's been cast like that snake skin up there, you really don't notice the yellowing much. The resin gets thin enough to not have a drastic effect on the end result.

 

[its_virgil]

The good news is that once you turn a blank down that's been cast like that snake skin up there, you really don't notice the yellowing much. The resin gets thin enough to not have a drastic effect on the end result.

That's true but once they yellow they are hard to sell. And, after someone purchases a newly cast blank then let's it sit in the shop for a few months then notices it has yellowed they often complain. I do turn them and use on pens. But I will stick with polyester resin for snake skins. Just saying.
Do a good turn daily!
Don

 

[jttheclockman]

That's true but once they yellow they are hard to sell. And, after someone purchases a newly cast blank then let's it sit in the shop for a few months then notices it has yellowed they often complain. I do turn them and use on pens. But I will stick with polyester resin for snake skins. Just saying.
Do a good turn daily!
Don

Like I said Don I have a couple of fiberglass blanks I bought years ago from CSUSA and whatever resin they used it yellowed just like the one you shown. Now Epoxy resins were not around back then so maybe it was alumilite, one of the early versions or silmar or some other resin. So my point is maybe you have had good luck but do not say it can not be possible to yellow. I also have many early versions of the computer pen blanks and they too have yellowed. Now these are old but still will yellow.

Now I use LD but I turn right away so no time to yellow. I wish there was a way to prove that the skin did not turn that blank yellow from the tanins in it. Skins may react differently in different resins too. Testing can only be done with time so if anyone want to do intensive testing and not sure how you can prove it. Unless you top coat the skin with a silmar coat and then cast in LD and leave for a year.