Commercial Painting Problems & Solutions: Blistering

Despite its benefits, Commercial Painting can come with a world of problems.  And one of the most common is blistering.

You’re probably working outside.  And the sun is probably beating down on you and the substrate.  But you’re painting away, minding your work, making sure there’s an even spread of material over the substrate, making sure there are no roll marks or brush marks.  and keeping a close eye on your wet edge.

But aside from your astute attention to detail, you begin to notice something a few hours after you’ve painted.  The thin film begins to bubble and create blisters.

Even though you were cautious and careful, minding your trade with disciplined workmanship, you’re still in disbelief that your finish is failing with these unsightly paint pimples.

Here’s what went wrong:

Painting in the Heat

Painting in the heat can have its benefits.  It helps the product cure at a faster rate, which means that the material can be handled or walked on sooner.  But it also has its defects.

After material is applied, the heat from the sun can cause the material to create a film.  And when the material attempts to cure, it gets trapped beneath the film, building pressure, causing it to bubble beneath the surface.  This is more common when applying a dark colored coating, because dark colors absorb heat more rapidly than lighter colors.

Painting Over Moist Substrates

This sounds obvious, but it’s not what you think.  The moisture isn’t on the surface of the substrate.  But instead, it’s within the pores and crevices of that substrates.  Commonly, moisture blisters occur during the winters.  Because the moisture that’s trapped in the substrate, isn’t as fluid.  And when the spring and summer months emerge, the moisture heats, becoming more fluid, is then released as vapors, which causes pressure build up, pushing against the coating to form blisters.

But regardless of the type of blisters, alkyd or oil paint finishes is the most common paint associated with these commercial painting problems.  Most oil based paints are sealer-type finishes, that prevents moisture vapor from escaping from the paint’s film.  This seal, although beneficial, can cause blister problems if there is a fluctuation in temperatures and humidity.

How To Prevent Paint Blisters

The first step is to figure out which type of blisters you’re dealing with.  Break open the blister.  If the substrate isn’t coated, then most likely it’s a moisture blister.  If the substrate is coated, then it’s a probably a heat blister.

Regardless of which type of blister, you’ll want to remove the blister.  Scrape the blister and the surrounding coating until you have sound adhesion.  Then, if there is not primer on the substrate, you’ll want to apply a primer.  This will help prevent any more moisture from vaporizing and escaping from this area.  If the area is already coated with a primer, then you don’t need to worry about a primer.

And once the area is adequately dealt with, you can proceed and apply the proper top coat that will seamlessly match with the surrounding paint.