Great question ioon44, the 1st coat in the most important.
This is a long winded response and is based on many tests and years of experience.
Grab a coffee.
Normally I just pre-heat the projectiles in a drying rack that is enclosed and has fans and heating elements. Only use this during winter and normally 10 minutes is plenty but mostly way longer than that because the drying rack will hold up to about 480kgs. I coat quite a few before I start baking.
I did some tests of short drying times when I was testing the colours.
My shed temp was reading 20.3 C and 43% humidity when I started but the temp was increasing and humidity was dropping.
1st coat the start temp of the bare projectiles read 20.9 C (interesting since shed temp was lower) projectiles had been sitting in a bucket near the roller door that had the morning sun on it so that may explain the higher reading or because of the infrared thermometer was reading a reflected surface.
Directly after the first coat the projectile temp was 15.1 C and they were left on a tray on a bench for 20 minutes.
After 20 minutes they were put into the oven and their temp was 20.9 C exactly what they started at. There was some heat coming off the roller door too.
After 1st bake the smash and solvent tests passed with no issues.
2nd coat the projectiles were 30.6 C still cooling after the first bake. Directly after 2nd coat they were 20.5 C and were left on the same tray for 15 minutes.
After 15 mins they were put back into the oven and their temp read 23.3 C. Shed was warming up and some extra heat from the roller door.
After 2nd bake the smash and solvent test passed without any problems.
I also did another test after 1st bake. Projectiles were 32.6 C before 2nd coat and 16.4 directly after the 2nd coat. I added metho to projectiles and then the coating so I would get a far longer tumble time and this chilled the projectiles more. These were left on the same tray on the bench and put into the oven after 9 minutes and their temp was 21.5 C. After the bake cycle they passed all tests.
During these tests there was no heat or fans used on the projectiles during the dry time. After about 5 to 7 minutes I spread out the pile to allow the touching surfaces to get some air as the touching locations remained wet for a longer time. After the drying time for each batch just before baking no coating would transfer onto my gloves, this showed that all surfaces were at least dry to the touch.
It should be noted that the weather and temperature conditions were very good for fast drying conditions when these tests were conducted.
The coating itself dries very quickly if it is exposed to air and, only the touching surfaces could transfer some coating onto your gloves quite some time later (10 - 20 minutes or more again depending on conditions and amount of coating applied) when the projectiles are moved around. Some damp spots will not cause coating adhesion problems.
I have found that once the coating is dry to touch or press, it can be baked. The issue is with moisture that is trapped between the coating and lead. Acetone is hydroscopic and also has a small percentage of water in it to start with. When the acetone evaporates it chills the alloy and attracts moisture. In extreme cases the coating may appear to go foggy, white or blushing, this is the attracted moisture and in the spay painting industry, we called it blooming.
Nice warm days with low humidity will mean less moisture. If it is cool and or high humidity the chilled alloy will attract a lot of moisture. In the case of cool temps and high moisture the coating will dry as usual maybe require slightly longer dry time however, there is trapped moisture and when the coating is baked, the surface of the coating may skin over and trap the moisture. The moisture will turn to steam and push the coating out of the porous surface effectively breaking the coating bond to the alloy and hench a failed smash test.
With an infrared oven from previous testing, the projectiles heat from inside out and may slow the skinning process of the coating which allows more time for any moisture to escape. This appears to be the reason I can bake projectiles after a short drying time.
Having said all that I am yet to conduct tests when the ambient temperature is cold with high humidity / dew point. I've always pre-warmed the projectiles in winter so I didn't have to worry about moisture related failures.
If you are concerned whether your first coat is dry enough (moisture evaporated) you could simply warm the projectiles. A fan heater or a hair dryer is all you need. As long as the alloy temp is warmer than the ambient temp you should get the moisture evaporated. You only need a few minutes after the coating is dry to touch.