Colored Spray Finish for Steel Roll-Up Doors

What's a good aftermarket color coat to apply to steel storage-shed doors that already have a coat of clear polyester on them? Pros give advice. July 3, 2008

I have a customer who would like a custom color roll up door. I have not found door companies that will custom finish. I have found one that offers a satin white (actually a very light gray). I want to know if I can spray a coat of Breakthrough on top of that to get the right color for them.

Does anyone here have the experience/knowledge with polyester to guide me on this? I could also spray a custom tinted polyester if that would be better. I like the idea of Breakthrough though as it is very flexible and I worry that additional polyester will build too thickly and possibly crack.

Forum Responses
(Finishing Forum)
From contributor C:
By roll up door do you mean car garage door? If not are you talking interior or exterior?

From the original questioner:
This will be more of the type sold for self storage units. It is an exterior rated unit but will be used indoors for this application. These are steel single sheet doors with horizontal corrugates for stiffening. Little wear on the door as the sides have nylon sleeves to slide easily in the tracks. They do flex though as they are rolled up and down with each opening cycle.

From contributor C:
I'm presuming you know for sure that this is a polyester door. If that's truly the case do you have experience in spraying two component urethanes? If yes, then I would sand and apply that since its an interior application and its less work and if sanded with 220/240 it will adhere well. This can be purchased at an automotive paint store or you can use Seagraves or others. The chemistry is quite similar in most. This is an acrylic urethane 2 component material which can be found in satins or flats or the normal auto gloss. The sheens will have to be purchased from a wood coatings company as Seagraves, Delta Labs, or many others talked about on here

From contributor R:
I would stick with the Breakthrough finish. Its easy to apply and tough as nails. Breakthrough can be purchased in a variety of colors and touches up rather easily.

From the original questioner:
Yes the manufacturer specifies that the finish is polyester, apparently this is commonly used in the industry for this type of doors. I have not used the two part urethanes but I have applied conversion varnishes.

So do you guys think that I should still sand the satin surfaces before applying the new color? Maybe I'll just use some coarse 3m faux wool pads or scrub with some medium pumice.

I'd love to do some speckle finishing but I don't think that they'll want it for this job. I did that on some ornate cast moldings to match up with some fancy cabinet finishes and loved it. The nicest thing is the way that the speckling (dark in this case) can adjust the shades of the molding. Since you don't need a wet coat you can just spray gently until the proper shade is achieved (much easier than adjusting the tint strength to a very accurate level). I really like the granitic appearance, though, and it is real quick to do.

From contributor D:
The adhesion is formed by mechanical sanding means when dealing with finishes such as these, so yes, sanding before applying another coating is a must. Failure to do so may be tragic. Err on the safe side always.