Elastomeric Coating. Why would it flash.

by Daniel May
(Casper, Wyoming)

I'm painting a concrete building. I've primed the surface and sprayed one coat heavy but I find that the SherLastic is showing lap lines. How do I get rid of them.

Please help.

Hi Daniel,

I'll first make some assumptions including firstly that you have applied a primer recommended for a SherLastic coating, along with the concrete surface being thoroughly cured, and your painting in a cool, dry (not hot) environment.

With those things being said, and without seeing the coated surface, I would venture to say that your paint sprayer needs to have a much higher GPM (gallons per minute) rating.

I do understand that the coating may look thick but it still may not be quite thick enough. Paint sprayers having at least a one horse power motor, tend to work best when spraying elastomeric's.

Another issue might also be your tip size. The recommend size is .021 to .025 depending on the thickness of the elastomeric being sparyed.

Try spraying your second coat in the opposite direction as the first (e.g. first coat up and down, second coat from side to side).

If after spraying on the next coat it flashes, then test out rolling a coat on to see if it fixes the problem (use a very thick roller cover to do so). You could also have someone roll while you spray.

Unfortunately, the problem with flashing is that it can sometimes be very difficult to eliminate once it appears.


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