So I found a decent work-around for cure inhibition. SiliNOT! is a reusable silicone substitute for mold making.
It melts at temperatures above 130°F (54°C), but they suggest not going above 150°F (65.5°C), as the material breaks down at 180°F (82°C). It can also be thinned with a small amount of water for detailed parts (I add water as it begins to melt and stir in as it melts further).
While it is only good for 1-2 pulls, the material is re-meltable to re-cast as needed. I use it for recently printed SLA masters, as I am too impatient to wait for photoinitiators to “burn off” and waste way too much silicone.
I use a sous vide system to get the specific temperature.
I’m not too familiar with mold making…Looks like that one die bled pretty bad, would it be the same with silicone?
Also how do you make sure the top of the mold is sliced at the right spot? Do you make mold up to that point, let it cure, then pour more?
That was a test die that I colored with markers.
Cap molds are a literal two-part process. The “bottom” is cast upside-down, as you adhere the dice to the base and pour the molding material over them.
For the “top” mold, remove the bottom piece from its mold form; flip it over; either cut out or remove your keys (voids that will fill in as part of the top mold, allowing for perfect alignment); coat with a mold release (I used petroleum jelly for this one, but will often use corn starch); put into your mold form; and pour your molding medium.
Ohhh that makes sense! I was “concerned” that something in the bottle was causing a chemical reaction. I’ve always wanted to make dice…despite only owning a handful of D6s
Do you ever have the top mold wind up out of alignment? Before this post I was picturing a one-piece mold and having to pour into a corner of a die which is obviously not a good method lol
I have had mis-fits on molds before, but cap molds will more often have raised face issues (cap did not seat all the way on).
There is a style of mold, often referred to as “sprue mold” that are single piece molds where you pour into the corner.
That’s cool, makes me want to try some casting!
Is there any specific reason to avoid silicone? I know one reason might be allergies
I was really worried about this because I hear it constantly. I did some tests using elegoo standard grey 8k resin and there was no cure inhibition at all with Dragonskin 30 silicone.
This isnt true for all resins but im glad I can skip a step because the tin cure I tried did not work well for dice molds.
Siraya tech has a line of resins that have similar properties. I have simply had limited luck with this (could be my cleaning/curing process, idk).
I found this stuff for a fool-proof solution.
I clean in 99% IPA for 10 minutes and then cure for 10. Overkill on both but that may help drive off the compounds that cause inhibition.
“Platinum cure silicone” is often the default mold material. It is durable, elastic, and mixes easily (usually a 1:1 ratio by volume).
An issue ue with it, however, is that it interacts poorly with dice masters printed from liquid resin (SLA printers) and will have trouble curing when it contacts the part. This leaves a gummy mess and ruined mold (not to mention a waste of money).
The remedy is to let the photoinitiators still left on the resin to break down. This can take anywhere from 1 - 2 months. As I am impatient, I tried the material in this post. With this mold, I can cast a part from epoxy resin and use that for making a standard mold.
Cool! What class of polymers is SiliNOT! made from?
Unsure, but I found this on their site: “SiliNOT! Non-Toxic is produced with food safe ingredients. Food-Contact Safe only applies when SiliNOT! Non-Toxic has been used exclusively with food safe casting material. Keep out of reach of children when heated. May contain food allergens. Contains citrus ingredients.”
Huh, so maybe some sort of algae or pectin derivative…