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Question How do I permanently seal water stains? (Posted by: Anonymous )

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Unsightly water stains can ruin the appearance of a ceiling or wall. Unfortunately, when eager do-it-yourselfers try to paint over a water stain, bleed-through tends to follow. Before attempting to paint over a water stain, learn the proper way to permanently seal the stain, or bleed-through is bound to follow.


When inexperienced amateurs try to paint over water stains, bleed-through often occurs. Ordinary latex paint won't adequately seal water stains. A base coat of primer can prevent a recurrence; however, plain latex primers aren't powerful enough to permanently seal water stains. To prevent bleed-through and encourage a uniform painted finish, choose a special type of primer specifically made to seal stains.

Essential Items


Roller frame

Roller extension pole

2 nap roller covers

Shellac stain-blocking primer

Denatured alcohol

Flat, satin, or eggshell latex paint

Canvas drop cloths

Step 1

Dust the drywall with a broom, or unseen dirt particles may cause adhesion difficulties. Primer and paint won't bond to dirty surfaces. Don't skip this critical step, or flaking may ultimately occur.

Step 2

Coat the water stain with a shellac stain-blocking primer using a roller. Ease the application process by attaching the roller frame to an extension pole. Roll vertically and apply light pressure to prevent ugly runs. Let the shellac primer dry for at least two hours.

Step 3

Wash the roller frame with nothing other than denatured alcohol. Dispose of the used roller cover in your usual garbage.

Step 4

Coat the primed water stain with latex paint, using a roller equipped with a fresh roller cover. Roll vertically and apply light pressure to prevent ugly runs and sagging. Let the paint dry for two hours.


If you need to seal a relatively small water stain, use a 2- to 4-inch paintbrush to apply the shellac stain-blocking primer. Unfortunately, if you use a synthetic paintbrush to apply the primer base, the nylon or polyester bristles will become misshapen. Opt for a natural-bristled paintbrush when working with shellac primer, or you may end up causing unexpected damage to your tool.

For attractive, lasting results, choose a satin or eggshell latex paint if you are working on an interior wall. Don't use an ordinary flat latex paint, or the finish won't be resistant to stains.


Be sure to cover underlying surfaces using drop cloths, or you could end up with unsightly stains. Don't use cheap plastic drop cloths, or primer and paint drips may pool. For best results, use absorbent canvas drop cloths.

Don't use denatured alcohol to clean latex paint from your roller frame; instead, use ordinary tap water. Likewise, don't try to use water to clean shellac stain-blocking primer from the roller, or you will ruin the tool.

Choose a flat latex paint if you are working on a ceiling. Don't use eggshell, satin or any other relatively high-sheen paint; these tend to conceal water stains and allow extensive damage to occur before the stain is noticed and the source of the leak is determined.

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Would be nice if the author had suggested some good brands of shellac stain-blocking primers. But the advice was very good and useful. By James on 03-03-12 at 01:22pm
I've been applying emulsion to cover water damage on an internal wall but the stains keep bleeding through. So I thought I'd Google the problem and see if I needed to seal the wall first. Bingo! This is exactly the answer I was looking for. Hopefully I can now apply sealant over the emulsion. I'll give it a quick sanding and brushing first. Fingers crossed. By Barbara on 15-06-14 at 10:36am
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