Re: SLA & RTV Molding

From: Joe DeGuglielmo (
Date: Sun Mar 01 1998 - 17:13:38 EET

We noticed this same thing early on in our RTV molding of sla parts.
What you are seeing is known as cure inhibition. It happens when you try
to make molds around sla parts that are not fully cured. The sla part
releases gases while it is curing. If you pour before its fully cured
the gas gets trapped between the pattern and the rubber. Some remedies
are to wait a bit longer before making the mold, check your PCA bulbs to
see if they are all working, leave the sla part in the PCA longer to
insure proper cure, and coat the pattern with a thin coat of Crylon
crystal clear. You should also revisit your build parameters, maybe your
not getting fully cured parts out of your machine.
Something has changed in your process since you were able to get good
results in the past. I hope this has been helpful. Good Luck.

Paul Rops wrote:
> RP Experts out there.
> I have been a long time subscriber and reader of email but have not sent
> any messages to the RP community.
> I now need help. We are using SLA masters to produce RTV molds. We have
> been doing it for some time using a tin catalyst base molding material.
> We were told that because of the materials we wanted to mold, the RTV
> molding material would have to be a platinum base RTV. We had initial
> success with this new RTV material, however, we are now experiencing
> non-curing of the RTV mold only at the interface of the Mold material
> and the SLA master. We are using Ciba-Geigy 5170 for the SLA Master. We
> have even recured the SLA Master for an extended period of time and this
> doesn't seem to cure the problem.
> Are there any answers out there?
> For more information about the rp-ml, see



Joe DeGuglielmo Eastman Kodak Company Rapid Prototyping Center 901 Elmgrove Rd. Rochester, NY 14653-5315 (716)-726-7046 Phone (716)-726-3220 FAX

For more information about the rp-ml, see

This archive was generated by hypermail 2.1.2 : Tue Jun 05 2001 - 22:45:01 EEST