DO NOT MIX STAINLESS STEEL AND CLAY MOLDS IN A FIRING. DO NOT mix different types of CLAY molds in a firing, always make sure that all your molds are of the same manufacture in a firing.
MAKE SURE YOUR MOLDS AND/OR SHELVES ARE KILN WASHED AND DRY EACH TIME YOU USE THEM!

When using molds ULP and ULR (large uplighters) and satellite dish, for the slump firing - use a program with a slightly lower top temperature - e.g. 785oC (1440oF) Using a hotter firing (800oC - 1470oF) will cause glass to avalanche’ down the mold, also use when doing “appliqué” enamel decoration in these molds.

Molds ONLY need to have the kiln wash layer removed when it is too thick to give a good impression to the glass. It will chip and flake when too thick, and also start to “fog” the glass when the layers are too thick. SOAK the mold in water, and then remove the layer CAREFULLY with an old credit card or similar plastic scraper, (not metal) until back to a clean clay surface. MAKE SURE you DRY the mold before using it, or the steam generated in the clay could burst the mold.

ULP, ULR, UFO1, UFO2, PLXL, XLFB, are all better with 6 mm (1/4”) or thicker glass.

Kilns which are deep enough to have more than one layer of molds should be stacked carefully to avoid extra heat build up. The stacking of the shelves should allow for a space equal to the height of the mold before the next shelf is placed. Care should also be taken not to have the shelf props touching the mold skirt, which could cause “hot spots”.

Molds should be stored flat, and if stacked, should have like sizes together, face-to-face only. Do not put smaller molds inside large ones, this could chip and damage both molds! The original packing box is also an ideal storege box.

Do not carry molds by only one side of the skirt, use both hands to support the entire weight of the mold. This is why the ‘hand-holds’ are cut into the skirt! This also applies particularly to the large diameter molds.

When washing off old layers of kiln wash, take great care not to lean too hard on the skirt of the mold while scraping the surface, this could cause minute cracks to form from the undue pressure, and the mold could then crack in the next firing. Remember that the weakest point is where the handholds are cut out, the skirt is narrower because of this.

When loading a kiln, take care not to push the molds against each other with undue force, or bump them against anything hard, as this could chip or crack them.

Regardless of the fact that all this sounds as if the molds are fragile, with the proper care and attention, they will give you a long and reliable service!

Due to the nature of the materials used for making the molds and the method of forming, a small difference in finished size can be expected from time to time.
Please check the size of molds before cutting glass. Glass should not be cut larger than the mold.