SEM 39673 Black Self Etching Primer - 15.5 oz.

This primer is the easiest to use self etching primer I've found so far and it adheres as well or better than anything else I've used for painting bare aluminum. It has a fine spray that goes on far more evenly than most rattle can paints. The primer dries quickly (three thin coats five to ten minutes apart are recommended) and can have the color coats applied after only an hour or so. While the can doesn't specify any temperature range for applying the paint, I have used it in 65-80°F temperatures without any problems. Obviously, the paint will dry faster at higher temperatures. Lower is better since the primer has to be liquid to etch the surface. The can does not recommend applying color coats directly to this primer (SEM doesn't specifically say so but a conventional primer should be used over the self etching primer), which is consistent with other self etching primers I have used which recommend using a regular primer over the self etching primer before applying color coats. I found that Krylon's Dual, a combination of primer and color coat, will work well when applied directly to this self etching primer, which reduces the overall number of coats of paint needed (the Krylon dries very slowly, though, although coats can be applied around 30 minutes apart). As always, proper surface prep is needed. I wet sand the surface with 320 or 400 wet/dry (which one depends how smooth a surface I want), then, after rinsing the piece with hot water and letting it dry thoroughly, I wipe it down with an acetone saturated cloth to degrease the surface (denatured alcohol or lacquer thinner also work well). While degreasing the work and handling it afterword, I wear disposable nitrile gloves to protect my skin and keep skin oils off the surface of the work. The price may seem high compared to other rattle can paints but is actually competitive with other self etching primers when you consider this comes in 15.5 oz. cans instead of the usual 12 oz. cans.

SEM products are of good quality. This can is in the current price range found from retailers. Fast shipping is a plus.

The nozzle has a nice fan pattern. I really like the self etching as my projects often sand through to small spots of bare metal and I prefer to always etch.

Finish really sticks. Looks like iron oxide finish after three coats.

This is the absolute best self etching primer we have found. We own a business and my husband frequently has to make up specialty brackets, panels, and trim on emergency vehicle installs. This primer adheres well to different types of sheet metal. Most importantly, it is durable, and does not peel or scratch off easily. We have had no issue with painting over it. It is our "go to" self etching primer and has outlasted any other brand we have ever used. It sprays evenly and we have not experienced any clogging problems with the nozzles despite repeated uses of the same can over an extended period of time. Highly recommend this brand.