What does flashing mean in house painting?

The color is uniform, but the sheen isn't consistent. This usually occurs over the holes and cracks you patched with a filler or drywall compound. The porous fillers absorb the paint, dulling the surface (a problem called "flashing").

Every time wet paint is applied over dry paint, it makes those areas have an EXTRA coat on them and the gloss level rises in those spots. This is known as "lapping" to me.

Flashing may occur over drywall or plaster patches where the wrong or zero primer was applied. We like a low-mid grade "dead flat" ceiling paint for priming patches.

MOST of my experience is that textured walls are the EASIEST to NOT have the flashing problem. Smooth drywall with ANY sheen to the paint is MUCH worse/harder to obtain a 'flash free' look.

A heavy coat with a thicker nap roller should do it, but don't blame me if it doesn't. Like I said earlier, the only way to be 99% sure is to prime the entire wall with the proper primer first.

I had a ceiling we did recently with a single coat knockdown on it. I primed it thoroughly and did one finish coat. When it was done, you could see what looked like sprayer tracks/lap marks. Upon further investigation it became clear that what was showing were flat spots in the texture where it was knocked down. You could literally see every stroke that was made when knocking down the ceiling, and no amount of paint would fix it.

Now, for flashing. This is usually when the sheen is flat, dull, or too glossy in some spots. This is hardly EVER a problem on textured walls because the light and shadow along the texture hides the flashing.

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