Preventing Stain From Ink Under Wallpaper

Just above my finger, you can see a bit of a green line.  A previous installer must have used ink to mark his plumb line .  Problem with this is, as you can see, ink will work its way through many substances, including wallpaper , and leave a stain on the surface. 
In this case, I removed the old wallpaper and then skim-floated the wall to smooth it.  As you can see, the ink, which is decades old (original wallpaper dates to the early ‘90’s ) is still active and has bled through the smoothing compound / joint compound .  If I were to prime and then hang wallpaper over this, it would work its way through both my primer and the homeowner’s new wallpaper.
So I’m sealing it off.  Above the green line you can see a strip of stain blocker brushed (actually daubed on with my finger) over the stain. 

I like to use KILZ Original oil-based stain blocker.  BIN shellac-based is another good product.  Don’t believe the claims on cans of water-based alternatives – nothing works as well to block stains as KILZ or BIN.  The fumes can be strong, and KILZ can make you high, so ventilate the room and/or wear a respirator when you apply this stuff.
Other substances / stains that can bleed through paint and wallpaper are tobacco , water , rust , marker , crayon , blood , oil , grease , food , hand prints , cosmetics , hair products , and so forth. 

Treating Water Stains

This window had leak issues ( rain , sprinklers ) some years back, which have been solved by replacing the window, and doing other repairs.  In the photo, I’ve applied my light blue wallpaper primer to the top half of the wall but not yet the bottom portion, so that’s why the color difference

Even though the leak has been stopped, vestiges of it are still appearing.  Water that entered the wall left vertical streaks on the drywall .  All these years later, after the paint and texture have been removed , the stains remain.

Water stains , along with some others, such as blood , rust , ink , marker , grease , oil, cosmetics , and the like, will bleed through joint compound , primer , paint , and wallpaper , creating new stains on the surface .  It may take a couple of months , but they will make an appearance . In this photo, I’ve already applied my blue primer. It only took a half an hour for these stains to work their way through.

This is the top right corner of the window , where the bracket for the mini-blinds is attached to the wall.  Note the stains on the underside of the window . 

To prevent these stains from working their way through the new coating / paint / wallpaper , it’s imperative to thoroughly cover them with a stain blocker .  And – trust me – water-based products won’t work, despite what the label claims.  You need an oil-based product like this KILZ Original , or a shellac-based like BIN by Zinsser .  Both are prone to splatter , so be sure to cover your floor and baseboards with dropcloths .  KILZ has strong fumes and can make you high , so ventilate or wear a respirator mask .  It’s a hassle cleaning the liquid out of the brush , so I use a cheap-ish disposable “ chip brush ” from Home Depot or Sherwin-Williams .  The products usually dry pretty quickly.
Note that wallpaper paste won’t stick to most oil-based primers , and shellac is too glossy for good adhesion , so I’m going to go over the stain blocker with my usual Roman Pro 977 Ultra Prime wallpaper primer , which sticks to just about everything , and creates a good, matt finish surface for the wallpaper to cling to.  

The Source of Yesterday’s Drama

Before I learned to put plastic over the smoke detectors, I’ve had sanding dust set off the alarm. But this is the first time that fumes from my primer tripped the blasted thing!

It was EAR SPLITTING, and went on forever! Finally I climbed up on the ladder and disconnected it from the power source. Still going off!! Turns out there was an alarm up on the next floor, that was also going off! Luckily the homeowner was reachable quickly by phone, and apparently this is a common problem in their home. She said to turn on the ceiling fan … and that did the trick.

I was smoothing a textured wall, and the penetrating sealing primer I like for that is Gardz, by Zinsser. The fumes won’t make you high like the KILZ Original that I used to use (even that never triggered a smoke detector), so I was surprised that it had anything in it to be detected by a smoke detector. Maybe it includes a carbon dioxide detector, and that somehow got tripped.

Either way, I’m sure glad we got the danged thing turned off … I like hanging wallpaper in peace and quiet so I can THINK!