[instock]

Occasionally, I work on these old houses from the 40's and they have plaster walls. There will be a few cracks in the paint. I go to scrape off the loose stuff and I find myself scraping off the whole wall! Under all the layers of paint, there is a really smooth, shiny surface. It's not surprising that paint has trouble sticking to it. I don't think that surface is paint. I think that is the actual plaster. But why is it so smooth and shiny?

 

[griz]

Occasionally, I work on these old houses from the 40's and they have plaster walls. There will be a few cracks in the paint. I go to scrape off the loose stuff and I find myself scraping off the whole wall! Under all the layers of paint, there is a really smooth, shiny surface. It's not surprising that paint has trouble sticking to it. I don't think that surface is paint. I think that is the actual plaster. But why is it so smooth and shiny?

Plaster can be notoriously slick.

You ever hear of lead base paint & RRP??...:whistling:laughing:

 

[instock]

You ever hear of lead base paint & RRP??...:whistling:laughing:

Let me rephrase that. I was going for brevity. What I meant to say is "When I point out to my customers that a proper paint job would involve stripping everything off and increase the cost of the job by a factor of twenty, they generally just tell me to just go over it and do the best I can." No RRP required. :thumbsup:

 

[instock]

Plaster can be notoriously slick.

Doesn't it get sanded like joint compound? Why were they sanding the walls with 1000 grit sandpaper?!

 

[griz]

Doesn't it get sanded like joint compound? Why were they sanding the walls with 1000 grit sandpaper?!

Probably a guy who knew how to use a trowel and not sandpaper...:thumbsup:

 

[Tom M]

I think they still only brushed the walls then too. Good thing that lead was self leveling.

 

[hdavis]

Doesn't it get sanded like joint compound? Why were they sanding the walls with 1000 grit sandpaper?!

The last step is polishing it almost mirror smooth with a trowel. There are tricks to getting paint to stick to old plaster. wipe it down with rags wetted with 10:1 water / distilled vinegar to remove any chalking and firm up / clean the surface. Use a sealer before painting or Kilz original has worked well in the past.

 

[griz]

Asbestos probably got something to do with it being troweled smooth...:whistling:laughing:

 

[hdavis]

It's not surprising that paint has trouble sticking to it.

I'd say paint sticking for 60+ years is pretty good - I' be happy with it.

I just had something pop into my head about 1940s houses. During WW2, regular paint was in short supply, so people resorted to this old stuff from the 1800s. Th resulting surface is a little more grey than just plain plaster, if that makes any sense. If that's what you have over the plaster, it all has to come off. Around here, it was used as a ceiling paint in the 1800s, and walls were wallpapered.

The nasty stuff is called calcimine:

http://www.oldhousejournal.com/cures_for_calcimine_ceilings/magazine/1015

 

[JHC]

Occasionally, I work on these old houses from the 40's and they have plaster walls. There will be a few cracks in the paint. I go to scrape off the loose stuff and I find myself scraping off the whole wall! Under all the layers of paint, there is a really smooth, shiny surface. It's not surprising that paint has trouble sticking to it. I don't think that surface is paint. I think that is the actual plaster. But why is it so smooth and shiny?

Its probably a layer of high quality lead based paint. :thumbsup: