What is a bonding agent?

I use it in areas that are hard or almost to sand correctly. Just spray it on prior to painting. Two coats are better than 1 thick one. The spray can variety can save you time and clean up. You can use the spray gun type and leave a little of the promoter in the gun and pour your paint directly into the cup and spray as normal.

DuPont has Mid Coat Adhesion Promoter.
Other brands include Bull Dog and Flash Bond 300.
All do the same thing. I keep a can of Bull Dog around because it comes in spray cans.

If you read my reply then you would see that I clearly said that this stuff is used where sanding is hard to do, or impossible to do correctly. I also said that the stuff works best if the surface has some kind of texture added to it by sanding or scuffing with a scratch pad.

If you go to the trouble of sanding down the entire surface to clean bare metal, then that would mean there was no hard-to-sand areas.

Some time when you have a few minutes to kill try this little experiment. Clean off the dirt from some old painted metal. Spray a light coat of Bulldog on it. Wait 10-15 minutes and spray again. Let the stuff set about 10 minutes and with a clean WHITE cloth wipe the Bull dog off. Look closely at the cloth and you will see the paint from the metal on the cloth. The Bulldog is softening the surface of the old paint to a point that is similar to fresh spray paint waiting for a next coat.

This is why the surface has to be almost sanitary in order to work correctly. It softens dirt and other contaminants and brings them to the surface to ruin an otherwise good paint job.

This little excercise is by no means scientific, but you can see that the stuff is working.

I use it in areas that are hard or almost to sand correctly. Just spray it on prior to painting. Two coats are better than 1 thick one. The spray can variety can save you time and clean up. You can use the spray gun type and leave a little of the promoter in the gun and pour your paint directly into the cup and spray as normal.

DuPont has Mid Coat Adhesion Promoter.
Other brands include Bull Dog and Flash Bond 300.
All do the same thing. I keep a can of Bull Dog around because it comes in spray cans.

I use it in areas that are hard or almost to sand correctly. Just spray it on prior to painting. Two coats are better than 1 thick one. The spray can variety can save you time and clean up. You can use the spray gun type and leave a little of the promoter in the gun and pour your paint directly into the cup and spray as normal.

DuPont has Mid Coat Adhesion Promoter.
Other brands include Bull Dog and Flash Bond 300.
All do the same thing. I keep a can of Bull Dog around because it comes in spray cans.