Resin casting molds for silicone: How do we cure solved problems
For a casting project we have a high precision casting mold with our SLA-3D-printer with made – printed eSun PLA Pro Clear Resin. As an impression material that came TFC BL200 silicone to use. The high detail of the cast was impressive – but there was one unexpected Problem: The silicone will not set to the contact surfaces of the mold.
Problem: Resin prevents the silicone curing
In the first experiments showed: The surface of the casting mold inhibited the curing of the silicone. Where the silicone came directly to the Resin in contact, it remained sticky or completely liquid, even after hours.
Cause inhibitory substances in the Resinthat probably during the UV-curing is not completely evaporate or degrade a well-known, but often overlooked Problem in the use of resin forms in connection with the silicone.
Solution: UV curing + heat treatment against yellowing & inhibitors
Through Research, we discovered a Trick that was supposed to be used Yellowing of transparent Resin to prevent – but it is precisely this effect solved our silicone is a problem.
The Procedure:
- UV-curing as usual with a daylight lamp or UV chamber
- Then: The Form for about 2 hours at 80 °C in the oven
- The yellow color disappears stitch – the Resin is again clear and transparent
- Seem to have been be inhibitory substances evaporated
We have this process repeated three Timesuntil the Resin when re-exposing no more yellowed – a clear sign that the majority of the reactive residue was removed.
Result: mold + silicone = perfect
After this treatment cured the silicone complete and reliable from. In addition, the surface of the cast iron was in the form of glass clear – a nice side effect, which facilitates the Handling and control during casting, improved
Note on safety
Important:
Please use not the kitchen oven for the heating of the Resin Parts, it's vapors can occur that are detrimental to health.
Instead, use a separate Laboratory or workshop stove with good ventilation.