Wednesday, September 12, 2012

Interior wall primer/sealer

This one goes out to PinkPig.

Q: Ok -- so what's the bestest, most nothing-bleeds-thru-from-underneath primer there is?

I have a kitchen[ish] area that was smooth coated about 10 years ago and I'm finally ready to paint.

[shaddap. It's a Fort - not a house.]


A; There are a lot of good primer/sealers out there and unless you are dealing with mold, mildew or something else really nasty like pet stains (another whole series itself), most all should work well. You said fort so if there are any arrow holes or blood stains, the sealer should work in one or two coats. (no not the arrow holes, patch those) They come in water based and oil based versions It sounds like you want the original oil based sealer. Ventilate well while using this, and have a good meal beforehand if you're applying a lot of it.

I once worked on a large house with extensive smoke damage from a fire. We tore out everything to the studs, wiped down all the piping, wiring and framing, then sprayed every surface with Kilz to seal any remaining smoke before we rebuilt the interior. We used maybe a hundred gallons and both the oil based and alcohol based worked just fine. Even with a respirator, I'd get goofy and nauseous, but less so on a full stomach.

The next question is whether you have any sort of grease or grime that the paint won't stick to, though generally sealers are better about going over problem surfaces than regular latex paint . Mold or mildew needs to be dealt with as well with a good quality product and allowed to dry well before covering it up.
Since it is smooth coated (I'm assuming a smooth layer of naked drywall compound with nothing else) look for obvious grimy spots and try a bit of the sealer to test adhesion. If it doesn't orange peel or ball up into droplets, you should be good. Otherwise you will need to carefully clean the surface with  TSP substitute to de-grease it. The raw plaster surface doesn't take well to being rubbed, especially with wet sponges. Use a big sponge such as a tile sponge and gently blot or wipe the problem areas and rinse with clear water. Let it dry well.

This would be a good time to patch the arrow holes, too.

If your surface is still smooth enough, seal away into the sunset. 

If not, do a fresh skim coat with thinned drywall compound with a wide knife or even a long trowel to even it out and when dry, gently shave any ridges with the edge of the knife and wet sand with your damp sponge. Then when it's dry you can finally seal it.  

Preparation is everything, especially if you want to make it last and not half-last.

So short answer is that I've had good experiences with Kilz oil based and recommend it for your purpose.  If you don't mind, could you send a before and after picture?