Warm Glass website

Information from the archives of the Warm Glass website and bulletin board.

Tips by Date                          Tips by Category    

Warm Glass website

WG Bulletin Board

Drying plaster/silica molds

Click here for basic information on plaster/silica molds for casting and slumping.

Although it's usually recommended that plaster/silica molds be air dried before firing in the kiln, that process can take several days.  With larger molds (or humid environments) it's not unusual for it to take a week or more to thoroughly air dry the mold.

For those who can't wait, there are several ways to speed up this process.  While these methods may be more risky than waiting for the kiln to air dry, they do save time.  And if done properly, they can be just as successful as traditional air drying.

The first method is simply to kiln dry the mold, using a slow firing schedule the allows for soaks at appropriate places to ensure that all moisture is driven from the mold.  This technique sometimes results in small cracks in the mold (especially if the walls of the mold are thick), but the mold is usually serviceable for firing and casting.

A second approach is to fill the mold with glass and then fire slowly in order to give the mold time to dry as the temperature increases.  This avoids the need for a separate firing to dry the mold and also makes it possible to fire plaster/silica molds fairly quickly after they have been poured. 

A third technique, which takes more time but is still quicker than air drying, is especially appropriate for larger or thicker molds that don't perform as well when fired in the kiln while wet.  This involves the construction of a drying box to speed up the drying process.  The drying box is inexpensive and fairly easy to construct.

All three of these techniques will be discussed in greater detail in future tips.


Copyright 2005 Brad Walker.  All rights reserved.

Click here to sign up to receive daily updates for the Warm Tips website.  These updates will come via email and will alert you as new tips are posted.


Got a tip to pass along?

Or a tip you'd like to see?

Four Corners International, Inc.

4140 Clemmons Road, #320

Clemmons, NC  27012   USA

Copyright 2005-2006 by M. Bradley Walker.  All rights reserved.

Designed, implemented, and published by Four Corners International, Inc.