Epoxy Resin and Silicone Molds

[dachshund1]

01-25

Gang:

Before I sheepishly share my latest casting fiasco - which may, once again, point to "user error" - allow me to ask two questions:

1) What's the proper maintenance for tube-in silicone molds used to cast clear, epoxy resin (e.g., Liquid Diamonds)?

and

2) What's the average life expectancy of tube-in silicone molds (again, for epoxy resins) - assuming proper maintenance?

A search of the IAP archives revealed few details - suggesting, perhaps, that this is tacit knowledge among the more experienced.

In advance, thanks for any info you're able to share.

Terry

 

[m4skinner]

I use Liquid Diamond some for tube in clear casting with ptownsubbie blue molds and use mold release.
the life of the mold was much shorter than I expected, not sure how many blanks I got out of them though.

 

[dachshund1]

Thanks for the reply.

This was my general experience also - even using Stoner thermoset release prior to each casting and keeping my molds clean. At the rate I've recently been casting (a lot, for me), I'd be replacing my molds about every 2-3 months using epoxy resin (e.g., LD).

I guess it's the added "stickiness" combined with a long set time, but this stuff is really tough on silicone. I'm contemplating either trying another casting technique or going back to Alumilite clear.

I'd love to hear others' thoughts on the matter.

Terry

 

[BeeAMaker]

PM instead

 

[McKenzie Penworks]

Have you considered going to an HDPE mold? tbarron (Tom Barron) here on IAP came out with a line of HDPE molds designed for tube in casting that allow you to do just about any tube. I've done probably 200 blanks with mine and they are as good as new. Even with alumilite I felt I wore out the silicone molds inside of 100 casts. I don't do tube in casting but my method requires single pours and I got tired of apologizing to buyers for my not quite straight blanks out of the silicone mold.

Man Eater Crafts is the trade name he sells the molds under, they're a little more money up front but you'll be glad you did it.

 

[dachshund1]

01-26

Thanks!

Since you're the second person to recommended this option - I went ahead and ordered one of Tom's HDPE molds to try it out. (I've been a past user of his gator-jaw pen blanks).

My results were actually decent with the silicone molds; I just didn't figure their usable life span would be so short.

Live and learn.

Terry

 

[McKenzie Penworks]

You'll be happy with it... The flexibility is awesome and it's not going to wear on you. DEFINITELY put mold release on the little plugs that go in the bottom though. I made the mistake of neglecting mine the first time and they got caked up after about 80 casts or so. Now that I'm putting mold release on them I'm at about 100 with no noticeable wear. This is alumilite though, I've heard LD can be a bit more sticky.

 

[longbeard]

I've been using the blue molds from Ptownsubbie now since he came out with them.
For the first month, I didn't use any mold release. They turned a light blue. Been using stoner mold release since, I have no issues with the molds getting any worse. I should of used mold release in the beginning.
I use West Epoxy Resin

 

[turncrazy43]

Check out the utube channel: Lost River Woodshop. He addresses your very question in his latest video.

Turncrazy43

 

[dachshund1]

01-27

Thanks - I hadn't seen this tutorial. Very informative.

From this, I assume that in curing, epoxy resins may generate more heat than urethane or polyester versions.

I'd be curious to know if, once the silicone becomes faded due to the leeching of oils, there is any method of "rehabbing" the mold? According to the video, it's toast and should be replaced.

I'm concluding from all this is that: (1) silicone molds may not be the best choice for frequent or production use; and (2) the use of epoxy resin, in particular, seems to limit their life span (presumably due to heat and/or length of curing time).

I've used silicone molds from several different makers - all of which have worked well and been of high quality. I think my lack of knowledge (and perhaps underestimating my frequency of use) simply led me to believe they would last longer than realized.

Again, all part of the continual trial-and-error that is casting.

Terry