Dissolving a cured 3d printed object

Hey Guys

I want to make a rigid mold of a 3d print so that I can cast it in a soft material. Is there anything that can dissolve or soften the 3d resin after the mold is made so that i can remove or break it out without damaging my mold.

I was thinking of trying flexible resin but it doesn’t print at 25um so grey resin would be optimal.

I’ll be making a composite epoxy fiberglass mold and hopefully after removing the 3d print, cast the object in foam latex which then cooks in an oven for a few hours.

It would be cool to hear from someone else that may have attempted something like this or may have some info on solvents that may work. I’m thinking of trying acetone first and just let it soak for a few hours.



I would try heat. If you put a (not high temp resin) part in boiling water they go quite soft.

Acetone will eventually dissolve it over days, but will also make it swell up which won’t help you.

Heat doesn’t melt the sla resins, you would have to burn those out.
Another option is to make a silicone mold of the 3d printed part then make a wax casting of it that you should be able to melt out easily with much lower temperature. Basically you would be making a core for your mold.

Alternatively you can use Remelt as your core. You will still need to make a silicone mold of the original 3d printed part first. I use remelt to make urethane copies of parts where the mold material is reusable but it can be tricky to work with since you use a microwave to heat it up and can bubble quickly. Remelt is available from Alumilite.com

Heat doesn’t melt it, but if will make it floppy, so it can be more easily peeled out of a mould.

Wax or Remelt core for the mold would probably be much easier than trying to pry out the softened sla print. I have heated sla prints and they become slightly flexible but will still shatter. There is a risk of having pieces left inside.

Another option is an additional silicone rubber part as a core depending on the shape. If it beefy enough you can use a low durometer silicone which will stretch and pull out. I had done that on a mold that was silicone and needed a threaded core which worked out well because it was reusable. I used the Remelt to make a temporary mold of my part. Next I filled it with a 20 shore d silicone which I simply inserted into the main mold.

I just did a mold for a silicone part, designed the mold in 3 outer parts and one inner core just like a cast iron mold design and it worked out very well.

You can try methylene chloride but highly flammable. There are other methods to do this right but I would have to see the model.

Just PRINT the rigid mold.

Using the high temp resin I guess? Would that work?

depends on the temp your gonna cook the mold at.
Tho I gotta say I am not sure why anyone would cast in oven cured latex and foam.

Epoxies can not take very high temps without pyrolysis or softening…
so I don’t see that as a solution- to oven bake epoxies they ought to be metal filled to act as a heat sink. But the heat needed for burnout of a resin would breakdown the epoxy casing.

But latex and foam is soooo 1970’s- you can cast RTV silicone parts at room temps for just about any durometer you need.- and if you absolutely HAVE to have foam… then you can get Self-Skinning urethane elastomer foams that cast at room temps and develop their own exothermic reaction.

The only trick to using self skinning urethanes is that the mold needs to initially vent to allow the foam to expand to the distal limits of the cavity, and then seal to allow the foam to build a very high internal pressure… its the pressure that collapses the foam on the inside surface to give you a solid rubber surface and foam interior.

to that end, any printed rigid mold needs to be robust- 1/8" average wall thickness with reinforcing ribbing to prevent the internal pressure from inflating the mold out of shape or bursting it.
Or you might print a thin walled mold, to capture an accurate cavity and separation plane, and then laminate some epoxy and glass on the outside of the mold casing for added robustness,.

Different densities of foam can be produced by simply controlling the amount of urethane relative to the volume of the cavity- with lower densities developing lower internal pressures.

Burman Foam in LA sells all kinds of foam supplies- they should have self skinning urethane foams in several different durmoters and densities.

oh- you can also do a mixed casting.

A simple sisal reinforced plaster mold can be made and you can cast liquid latex in it like you would slip cast ceramic- fill it up, wait ten minutes, then pour out the liquid to build a surface skin on the mold interior.- then when the latex is pretty firm but has not shrunk much- pour in some urethane foam that will expand to fill the cavity.

This will give you a latex exterior with urethane foam interior.

to paint self skinning urethane parts- use elastomeric urethane paints.
for latex- you can use the same paints- or you can mix pigments into liquid latex cut with ammonia and water - test first because cured latex does not pigment as you would expect-
but pigmented latex paint can achieve 150% elongation without cracking.