It really depends what the weather is doing where a guy lives.In the summer months the shop is warm and flash time is minimal.In the winter even though the shop is warm I like to put the infrared light on the panel to get the metal temps up before I prime,then after I apply a coat put the light back on.I keep doing it this way for each coat until I am finished,it really cuts down on time and shrinkage.If a person is careful with distance you won’t have to worry about possible blistering and solvent pop.Nice gentle heat is all you need.
Agree with Jayson – gentle heat. My booth is also unheated so I use heat lamps in the winter but have to be careful not to get them too close otherwise you bake and seal the top before the underneath has flashed, leading to solvent pop later.
Most infra red lamps have a flash off function, flash off function can be used for drying between coats.
Over the years I have used medium and short wave lamps, Last year i bought a new shortwave model, they are a major improvement on medium wave models.
I always bake my primers, even if they have sat overnight i would still put the lamp on them for ten or fifteen minutes in the morning, if the primer is fully cured, i find there is much less chance of any sinkage etc.
I have two lamps a three cassette model and single cassette model they are used daily and i wouldnt be without them lol.