This is another oldie-but-goodie technique to achieve a smooth finish when using common spray can paint. I thought this was method was pretty well-known, but I occasionally run into folks that have never heard of it.
Warning: This is one technique where common sense needs to prevail. Don’t use heat exceeding the manufacture’s recommendation found on the can, usually 120 degrees Fahrenheit. I also would not attempt to use other methods of warming the paint, such as open flames, torches, ovens or similar. No doubt people have used these approaches, but this is too risky. Paint cans *will* explode if excessively heated.
The process couldn’t be easier, using hot water from the tap, fill a container and immerse the paint can in the water. Use the hottest water you have available, within reason (see “Warning” above). I wouldn’t boil the water for instance as that would too hot and could be dangerous. Leave the paint in the hot water 20 minutes to a half hour or so, longer won’t hurt anything. Personally, I like to leave it for at least 30 minutes, dumping out the water about half way through and refilling with fresh hot water. I also shake the can well a couple of times during the soak process.
When done soaking, dry off the can, shake it well and you’re ready to go. This works equally well on primer or finish paint and really does help in laying down a nice, smooth finish.