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Oil or latex on plaster?

I have received so much conflicting advice that I am completely confused!  We have scraped paint peeling from a plaster bathroom ceiling in our 1940 house.  l have scraped all of the paint that will scrape off and there are still areas of the ceiling to which paint is FIRMLY affixed.  I have asked specialty paint store people and everyone else that I would consider more experienced than me.  Everyone says something different!  From "Use joint compound to even out rough patches and then use an oil based primer and then use latex paint."  to " Don't use oil-based primer - it will just soak into the plaster!  Use latex Kilz and then paint."  HELP!  Do I use joint compound?  Do I use oil-based primer?  Do I use latex? And can you explain why I should use one over the other?

Thanks for any feedback!

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Posted 2013-07-27T18:35:31+0000  by oldhouseblues oldhouseblues
 

If you've removed paint down to the plaster on a house from the 1940's the odds a very good that the paint contains lead.  You might want to read up on that.

 

Now let's talk about your project.  You've removed the paint, down to the plaster, in some areas and not in others leaving an uneven surface.  If you even out the low spots with drywall compound, what will you be painting?  The existing paint and drywall compound?  Any plaster is behind paint or behind drywall compound.  There's no reason to use an oil based anything unless you have some other problems you're trying to cover (and haven't mentioned).  I'd use a good quality, latex primer over the entire surface (make sure the existing paint is clean) and paint with your favorite paint.

 

As for drywall compound, for small projects I prefer the powered lightweight "setting" compounds.  "Setting" means it hardens via a chemical reaction vs. evaporation like premixed joint compounds.  They come dry, in a bag, and you mix it with water to the consistency of peanut butter.  You just mix what you need.  Kept in a cool, dry place the stuff will last a long time.  Need to patch a couple of nail holes?  Put a couple of teaspoons in a paper cup, add a few drops of water, mix with a putty knife, and you're in business.   They come in a variety of setting times, from 5 to 210 minutes.  The actual working time is about half the setting time (and depending on conditions the setting time can be longer).  I find the 90 to be a good balance of setting time and working time.  Cheap too.  $7 for a bag.

 

 

 

Posted 2013-07-28T03:26:45+0000  by Adam444

According to the Zinsser Company, their 1-2-3  water based primer is the primer of choice on bare plaster. Zinnser publishes a quick reference sheet on suitable primers  which most Home Depots have.

 

Easy Sand 20 was my patching material of choice. It does sand easy, adheres extremely well, sets fast and, if you live in a cold climate, it does not freeze in your work truck overnight. I always carried a two gallon bucket of it in my truck. The bucket was air tight and kept the moisture out. The 20 minute variety was jus a compromise. If you need more time, buy the 45 or 90 version. If you are in a hurry, mix the 20 version with warm water.

 

 

Posted 2013-07-28T03:48:35+0000  by ordjen

Thank you for your quick reply!  I appreciate the explanation and I will try what you suggested.  

 

On the Lead Paint removal note...that is all I have researched since I saw your reply!  I was under the foolish impression that lead paint was mostly in the trim work where children might chew (i.e. the window sill)!  I am concerned that I have exposed us to lead dust!   The bathroom ceiling we scraped was small and the paint was peeling off.  I had a window open for ventilation because there is no air conditioning vent in the bathroom and the door was closed.  We used N95 face masks because we didn't want to breathe the dust anyway.  I did scrape the paint when it was dry. :( Hopefully we didn't breathe in a great deal of dust but I'm not sure how to know for sure.  Yikes!  It is my teenage son's room, so I'm making him sleep in a different room tonight so I can clean more tomorrow.

Posted 2013-07-28T04:59:00+0000  by oldhouseblues

Also, thank you to Ordjen for the fast replay!  I'm not as familiar with Zinsser products and I'm glad to know that a primer specifically lists bare plaster!

Posted 2013-07-28T05:03:33+0000  by oldhouseblues

Unfortunately they put lead in all kinds of paint because (according to Wikipedia), "Lead is added to paint to speed up drying, increase durability, maintain a fresh appearance, and resist moisture that causes corrosion."  Trim is commonly mentioned because that's what young kids were found to chew on (it's much tougher to chew on a ceiling). :smileyfrustrated:  I don't have the knowledge to make any "what should I do now" suggestions other than to say avoid disturbing any more paint without using the correct removal techniques and personal protection equipment. 

 

Your other option with this project is to simply cover the entire ceiling with a layer of 1/4" drywall.  Mud, tape, sand, and paint.

Posted 2013-07-28T13:26:49+0000  by Adam444

 

White lead was the main paint pigment in quality paints up to 1973 when further manufacture was banned. It was still legal to sell existing stocks until 1978. An older pre-70's house is almost certain to have some lead paint in it somewhere. This ol' painting contractor put many a gallon of lead paint on homes back in his early career in the 60's. He also sanded much of it off in the following couple decades. How much IQ was lost i don't know :smileysad:

 

The main concern is for kids whose bodies and brains are still developing. Even then, the concern is for continued exposure. Try to keep the old paint encapsulated, tryng not to disturb it anymore than neccessary. Isolate the work area. Wear a good lead rated mask and wash your work clothes promptly.

Posted 2013-07-28T15:50:22+0000  by ordjen

Thanks for the info, ordjen!  Your post makes me feel better because I've worried quite a bit after reading info on lead paint!   The bathroom ceiling has been scraped but I won't scrape any paint in here again without ALL of the lead paint precautions!  I've washed everything possible and I take a little comfort knowing we at least had masks on and there was no air vent in the room.  This was the only room I've ever scraped paint from, so hopefully my teens haven't run into much lead paint exposure.  

 

Just for the record, I'm sure you didn't lose a single point on the IQ!!!

 

Thanks again for easing a mom's worry!!!

Posted 2013-07-29T03:34:48+0000  by oldhouseblues
 
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