Natural drying first. The lamps are the backup, and they work.

Nobody films heat lamps, which tells you something. What gets filmed is the same physics with a different tool: a potter with a torch on a wall that is about to fold, warming it for thirty seconds and going back to throwing. The lamp is that torch, slower and wider, and the rules are identical. So the videos below show heat being applied to wet clay on purpose, and this page carries the part the videos leave out, which is the slab mold rule, the timing, and the list of things heat should never be used on.

Read the jobs and the non-jobs first, so you know what you are watching for. Then watch a torch stiffen a pot. The words give you the judgement and the video gives you the timing, and you remember both better together than apart. Then go set a timer and stand next to the lamp with a piece that actually needs it.

A heat lamp dries the surface facing it, fast. Let clay dry on its own whenever there is time, because even drying is what stops cracks. When there is not, the lamp is the backup: a piece on a slab mold takes ten to twenty minutes, checked every five and turned, and comes off the mold the moment it holds its shape, because the clay shrinks as it dries and the mold does not, and a few minutes too long splits it. Anything not on a mold takes short bursts, turned, stopped when the surface goes matte. A cotton sheet over it afterwards lets the skin and the core even out. A minute rarely hurts anything. Fifteen or twenty unattended can.

Ten to twenty minutes on the slab mold. Check at five, ten, fifteen. Off the moment it holds.

Check at five, ten, fifteen. Off the moment it holds. Bring the mold to the lamp with the piece on it, set a timer for five minutes, and stand it a forearm’s length under the heat. At five minutes, turn the mold a quarter turn and touch the piece: a knuckle pressed gently into the wall should leave a mark and spring back. At ten, turn again and test again. Somewhere between ten and twenty minutes the piece will hold its shape when you ease an edge off the mold, and that is the moment it comes off, onto a plastic bat, whether the timer says twelve or nineteen. The number is a range because slabs differ in thickness and molds differ in size; the test is the edge lifting clean.

Check at five, ten, fifteen. Off the moment it holds. Mold under the lamp a forearm’s length away, timer set for five minutes. At five, quarter turn and a knuckle test. At ten, again. Somewhere between ten and twenty minutes an edge lifts clean off the mold, and that is the moment it comes off onto a plastic bat, whatever the timer reads. Past twenty, the clay has shrunk and the mold has not, and the piece splits at the rim or a corner.

Here is why the clock matters. The mold is plaster or bisque or plastic and it does not shrink. The piece on it shrinks the whole time it dries, and it shrinks fastest under the lamp. On a hump mold, where the clay sits over the outside, the piece tightens onto the form like a shirt shrinking on a hanger, and past a certain point it tears, usually at the rim. On a slump mold, where the clay sits inside, the piece pulls away from the walls, which is what you want, but a rim that has gone stiff while the base is still soft cracks when the base finally shrinks. Either way, twenty minutes is the edge and thirty is a split.

Turning matters as much as the clock. One face under the lamp for fifteen minutes is a piece that dried on one side, and a piece that dried on one side warps toward the lamp and cracks on the far side. A quarter turn every five minutes is the whole habit. Shield a thick rim or a thick base with a bat if one part is getting ahead.

When it comes off, it goes on a plastic bat under a cotton sheet, and the mold goes back to its numbered spot, cleaned. That is the sequence the clean-up page asks for, and the lamp is what makes it possible on a short night. Our slab mold lesson covers the rest of the mold work.

A sheet over it for half an hour, then carry on.

Cover it, then continue. A piece that has just come off the lamp has a dry skin over a wet core, and it is not stable yet. Keep working on it immediately and the skin softens as water migrates outward and the piece goes floppy again, which feels like the lamp did nothing. Set it on the shelf uncovered and the skin keeps drying while the core is still wet, and you have made the crack you were trying to avoid. The answer is a cotton sheet, loosely, for half an hour to an hour. Under the sheet the surface stops losing water, the core sends its water outward, and the whole piece settles at one even stiffness that will actually hold.

Cover it, then continue. A lamped piece has a dry skin over a wet core. A cotton sheet loosely over it for half an hour lets the two even out into one piece that holds. Then finish the work, or cover it properly for the night; a lamped piece never goes on the shelf uncovered.

After the sheet, finish what you were doing. If the job was a slab off a slab mold, it is ready to trim, join or texture. If it was a wall that needed to stand for the last pull, take the pull. If it was a build that needed to take more coils, add them, and keep the new join soft with a damp sponge.

Then the piece dries like any other piece, which means slowly and evenly: a plastic bat, a cotton sheet, and days. A lamped piece is not a head start on drying. If anything it wants a sheet more than a piece that was never lamped, because its surface has already been pushed ahead of its core once. Our sheets and bags lesson is the next page to read.

For brush-on glaze there is one more use, and it has its own rules. A coat that has to dry before the next can go on will dry in a minute under a lamp instead of ten in the air. Stop the moment the sheen goes matte, keep the piece turning, and never let the coat go chalky; a glaze coat driven too dry by heat cracks like mud and crawls in the kiln. A hair dryer does the same job with less risk, and the brushing lesson covers the coat-by-coat rhythm.