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August 5, 2009
Paint Prep: Old Paint Peels Off?
I’m prepping a room for repainting (building built in 1920’s). One curious thing: I have interior doors that when I take a putty knife to them, the paint comes off pretty easily in sheets. I have ‘sheets’ of paint that are flexible and that are the size of a poncho. I can get a piece like this stripped off pretty much just by pulling on it with one hand and using a putty knife behind it to separate it easily from the door…when I do this, a very fine powdery dust is released from the underlying paint surface (the paint underneath is a different color). My suspicions are that the ‘sheet’ is thick latex paint (maybe a few coats) that was painted over a previous oil-base paint and that it didn’t adhere well. Btw, the underlying paint isn’t glossy
Anyway, before repainting these doors, are there any recommended preparation procedures and/or product(s) recommended to use to assure proper adhesion with the new paint? Maybe a certain primer? I was thinking of wiping the doors down with either water or mineral spirits (in the event there is a fine dust layer still there). I’ll be repainting the doors with latex interior paint, probably Benjamin Moore).
Thanks.
Comments
Absolutly yes.
It sounds like your suspicions are correct, that latex was put over oil. To do this properly, the old finish should be sanded lightly with 100 maybe 120 grit paper to allow a "mechanical bond". Then primed with an oil base primer. I have recently used a product called Styx which I was very pleased with (I've noticed that Pitchnik carries a Stxy product, though not the one I am familiar with). But Ben Moore makes an oil base undercoater that the paint stores recommend for use between unlike paints.
Feel free to call me it you have any questions, I don't mind answering questions if I have the time.
Steve
www.thetinkerswagon.com
Posted by: thetinkerswagon at August 5, 2009 8:54 AM
Be mindful that house paints used be made with lead, so that fine dust should not be inhaled or ingested, especially by children.
Posted by: Maly at August 5, 2009 9:56 AM
Thanks for the replies. There's no children here, but I'm mindful of the lead issue and am handling it safely.
Steve, thanks for the info. I do not see your phone number. From your description, the primer you recommending sounds like an oil base product: are you suggesting that the doors/frames be repainted with an oil base paint, as opposed to a latex base paint? Would latex paint be able to be applied over the oil base primer you referenced?
Thanks again.
Posted by: Oxygen at August 5, 2009 12:28 PM
Hi Oxygen,
I believe Steve is correct in that latex paint was put directly on top of oil. Happens all the time, but the bond is poor, as you discovered.
The doors and frames will need an oil-base primer, after which you can apply a finish coat (likely two) of latex or oil. If latex, you will want an eggshell or semi-gloss on woodwork. Some manufacturers have variants on that theme. Sanding need only be light, just to roughen up the surface a bit.
Although oil-base primers are more difficult to clean up after and are fumier (VOC's), they provide superior stain hiding and bonding performance over latex-based primers, which should only be used on new drywall or knot-free wood. I have had excellent luck with the high-hide version of Bins (avoid Kilz). Available at HD.
If you are doing this yourself, get the right brushes for the right paint.
Posted by: renomandru at August 5, 2009 6:13 PM
rneomandru,
Thanks for the Bins tip. I do have good Purdy brushes that lay it on smooth.
Btw, what sheen did you paint your walls with the F&B paint?
Posted by: Oxygen at August 6, 2009 11:48 AM
How's it coming? Purdy makes nice brushes.
We used what the call the "estate emulsion" for the walls, which is basically very flat. This one has all the clay. We used the "water based eggshell" for the woodwork. Contemplating an oil-based paint for the doors themselves, but haven't gotten to them yet.
Posted by: renomandru at August 6, 2009 11:28 PM
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