Mystery layer on top of drywall

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Old 09-12-09, 10:01 PM
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Mystery layer on top of drywall

We have just finished the miserable job of removing wallpaper from our large master bath and are preparing to paint.

Beneath the wallpaper (top printed layer and bottom brown paper/gluey layer) is a greyish-white layer of something on top of the dry wall. In some places, the water used to remove the wallpaper caused this white layer to bubble up or blister and come off when I scraped off the wallpaper.

I am baffled as to what this layer is. It is clearly NOT the top layer of the drywall, which remains intact; could it be a primer, or some kind of "sizing"? There's no way we can scrape it all off; I imagine some more of it will come off when I thoroughly wash the walls to remove any remaining wallpaper paste.

Any ideas as to what this is? How should I deal with it when prepping to paint?

Thanks.
 
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Old 09-13-09, 05:04 AM
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I don't remember what it's called but sometimes a paper underlayment/backer is used to even out the wall and hide cracks before the paper is hung. If so it should remove fairly easy with water and a wide putty knife.
 
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Old 09-13-09, 07:03 AM
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Originally Posted by marksr View Post
I don't remember what it's called but sometimes a paper underlayment/backer is used to even out the wall and hide cracks before the paper is hung. If so it should remove fairly easy with water and a wide putty knife.
That would sound quite reasonable; however, could something like that "morph" over 15 years into something resembling a thin layer of paint or similar? It currently doesn't resemble paper at all.
 
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Old 09-13-09, 07:34 AM
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Just a guess but you make be encountering "sizing" or "wall Sizing" which is a wallpaper "primer" made usually of either a diluted wheat paste which is old timey wallpaper adhesive or a diluted adhesive like material.It also could be a wallpaper primer depending on how long ago the room was papered.

Wallpaper needs a layer between the adhesive and unprimed drywall to prevent the adhesive from grabbing so hard that it penetrates the outer paper and grabs deeper.This is applyed so that future people like yourself won't destroy the walls trying to remove the wallpaper.

From another site:

"Primers - Sealers - Sizing

Wallpaper must resist the force of gravity to stay on the wall. However, its grip on the wall mustn't be so strong as to damage the wall in the event you wish to remove the paper at a later date. This is a tough balance to achieve. Primers, sealers, and sizing are designed to create the necessary base so that adhesives can stick well and that wall coverings can be removed with little damage to the wall surface."
 
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Old 09-13-09, 08:25 AM
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Originally Posted by spdavid View Post
Just a guess but you make be encountering "sizing" or "wall Sizing" which is a wallpaper "primer" made usually of either a diluted wheat paste which is old timey wallpaper adhesive or a diluted adhesive like material.It also could be a wallpaper primer depending on how long ago the room was papered.

Wallpaper needs a layer between the adhesive and unprimed drywall to prevent the adhesive from grabbing so hard that it penetrates the outer paper and grabs deeper.This is applyed so that future people like yourself won't destroy the walls trying to remove the wallpaper.

From another site:

"Primers - Sealers - Sizing

Wallpaper must resist the force of gravity to stay on the wall. However, its grip on the wall mustn't be so strong as to damage the wall in the event you wish to remove the paper at a later date. This is a tough balance to achieve. Primers, sealers, and sizing are designed to create the necessary base so that adhesives can stick well and that wall coverings can be removed with little damage to the wall surface."
Sounds as if this might be what we're dealing with. I'm hoping that the rest, or at least most, comes off when we thoroughly wash the walls, or when I sand before priming. One thing I don't want to have to do is scrape another layer of anything off those ridiculously high walls!

Thanks!
 
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