It’s an age-old problem that can catch you unawares. It shouldn’t happen in an established shop with experienced staff and good quality control, but things can change. New staff, undetected equipment failure, lapses in quality control especially under pressure and when short-staffed, and a half-dozen other things can happen and you suddenly have a plastisol under-curing problem.
If it does happen, it can be an expensive proposition if not caught early. What you definitely do not need is to discover a curing problem after the whole order has left the shop. So, the obvious advice is to check for proper curing regularly throughout the run no matter what other pressures there might be to take short cuts.
If and when you do catch an under-curing problem here is a reference list of possible causes and solutions . . .
The dryer temperature is too low. Use a thermo-probe to check the temperature at every point on the journey through the dryer. If it is not reaching cure temperature then turning up the heat is the obvious solution.
The dryer temperature is fluctuating. Check for open doors or windows that might be allowing a cold draft to flow through the dryer. This cause has baffled more than a few printers over the years, especially in summer when the shop can get very hot and doors or windows are opened to provide some relief.
The dryer belt is overloaded. Reduce the number of garments on the belt at one time – space them out more.
The garments are being placed on the belt improperly. Make sure that the garment is flat on the belt so that its imprinted area is fully exposed to the heating elements.
There is excessive moisture in the garments. Run the garments through the dryer before printing them. A forced-air dryer is best for this.
Ink additives have been used improperly. Make sure that ink additives (type and quantity) are used strictly according to guidelines.
The prints have been over flashed. Over flashing can adversely affect inter-layer adhesion causing the layers to peel or flake.
Of course I hope that you never have to consider these causes, but stuff happens, even in the best of shops. And if it does, I hope that the reminder list helps.