preparation on walls for painting

[truck90278]

We are in the process of remodeling my son's kitchen.  It is an older home (1940s) and has plaster walls. As we are preparing the walls for paint (patching, etc) the old paint has come off in many places in sheets.  Some is due to painting over plaster patching and probably bad priorm paint preparation in it's former life.  So we have been sanding the walls with 40 grit paper with our RO 125 getting down to pretty much the original paint. The question is what would be the appropriate grit for finish sanding - we will have some repairs with sheet rock also?  We are thinking 120 grit. We will be priming the walls prior to paint

 

[Brice Burrell]

Well, I wouldn't worry too much about getting the paint sanded to fine finish as I would about getting it clean.  The previous paint job is likely coming off because the grease wasn't cleaned off before painting.  I'd guess the biggest problem areas are were the stove is/was.  I suppose you could hit the paint with 80 then 120 just to get the nasty scratches out.

 

[tjbnwi]

Could be effervescence causing the paint to come off. If that is the case you'll need to strip and reprise the walls.

Has your son had the house/walls insulated? It being a '40's home I doubt there was any when it was built.

Tom

 

[truck90278]

thanks all for the comments, we will move forward and we have yet to get to insulation.  Just not wanting big scratchs from showing when we are finished.

 

[Holzhacker]

Stop sanding the walls. Waste of time and potentially hazardous.
- That age house could easily have Lead paint. If you are sanding without proper precautions, and even then, you may be contaminating the entire home with Lead paint dust.
- Before you decide to patch plaster walls you need to assess how much dis-bonding there is. If the plaster is still firmly attached to the lath, you can patch. If the plaster is bulged out a lot and detached from the lath, patching is just another repair that will have to be re-done again. Minor dis-bonding can be dealt with in various ways.
Straight plaster can be difficult to deal with if you aren't good at it. A more forgiving method:
Structo-lite with about a 1/4 durabond. You need to add the DB otherwise Structo takes forever to dry. Also the Structo will roughly double the dry time of DB; turns 20 into 45 etc. This mix floats well, hides all evils, breathes so it cures well, and can be gone over with mud very easily for a nice finish. Sand to 120.

 

[leakyroof]

Stop sanding the walls. Waste of time and potentially hazardous.
- That age house could easily have Lead paint. If you are sanding without proper precautions, and even then, you may be contaminating the entire home with Lead paint dust.
- Before you decide to patch plaster walls you need to assess how much dis-bonding there is. If the plaster is still firmly attached to the lath, you can patch. If the plaster is bulged out a lot and detached from the lath, patching is just another repair that will have to be re-done again. Minor dis-bonding can be dealt with in various ways.
Straight plaster can be difficult to deal with if you aren't good at it. A more forgiving method:
Structo-lite with about a 1/4 durabond. You need to add the DB otherwise Structo takes forever to dry. Also the Structo will roughly double the dry time of DB; turns 20 into 45 etc. This mix floats well, hides all evils, breathes so it cures well, and can be gone over with mud very easily for a nice finish. Sand to 120.

. Thanks for the info.