Some questions on primers

[lc155]

Hi,

Began doing a room redecoration project not too long ago, just doing a few bits every day and slowly making my way through it.

It's an old house with lath and plaster walls, so the walls aren't in the best condition. I've opted to replace the old paper with newer paintable paper (so it can hide the bumps, etc.).

What I've done so far is peel the vinyl top layer of the old paper off, then wet the backing paper and peel that off. From there, the lining paper that's stuck to the actual plaster walls looks very sound, so I've opted to keep that on and just re-paste down any loose areas with the wallrock readymixed adhesive, as it seemed to be highly regarded for its strength.

After that, I opted to seal the lining paper with Zinsser Gardz (needed more than one coat tho as not all areas of the paper were equally absorbent, so getting it nice and shiny took some do-overs). After the first coat I also very gently took a fine grit damp sanding sponge to the surface of the paper and gave a couple of quick passes, which removed all the rough bits of what I presume was old wallpaper adhesive. This got everything nice and smooth.

First question: Was this the correct method, sealing the sound lining paper to the wall with Gardz, with the intention of papering over the top of that shiny finish? (will be using the wallrock adhesive again). Most people who Gardz over old paste do it with the intention of painting over it, I'm just looking to paper over it again, so sealed and 'sized' the lining paper, treating it as a bare wall. I'm just hoping that the shiny surface finish of Gardz doesn't prove problematic for wallpaper adhesion, no issues with seams coming off, etc? I have bad experience with poorly painted satin paint causing wallpaper around skirting edges to come loose, so I am a bit paranoid there!

Second question is, when I come to do the ceiling. It was previously painted in a shiny satin finish, and I want to go over it with a matte paint, but am worried about crazing. I can't sand it to key because it's a textured paper that was painted, so I need another solution. I have heard you can just apply Gardz to that as well, and it will be good for coats of paint after.

Others say that Gardz is not the correct primer for this job, and Zinsser 123 is what I want. What's the recommendation here?

Cheers.

 

[opps]

You didn't need to seal the old lining paper but doing so isn't a bad thing. When papering over old lining paper, you can find that the adhesive reactivates the old paper's glue, causing it to bubble. Most of the time the bubble shrinks back as the new paper dries but it can be a bit of a pain it it happens over a join in the new paper. Given that you have applied the Guardz, you shouldn't have that problem.

Assuming that you have a decent brand of matt emulsion, I would just paint straight on to the ceiling. I would only have concerns if it were a shower room ceiling and subject to very high levels of humidity. And were it so, I would have recommended water based eggshell anyway.

I have never used Guardz, I normally use their BIN for "problem" areas. Guardz would have been useful if you had wanted to paint on the old plaster and weren't certain that you had removed all of the old paste.

Having used the Guardz, you will find that the water in the wallpaper will take longer to evaporate as it can only evaporate in to the room (rather than some soaking in to the wall). It will not affect the adhesion.

I don't know how much experience you have of working with lining paper but I would suggest you consider using a roller to apply the paste rather than a brush and use a "caulking blade" to smooth the paper.

https://www.toolstation.com/prep-caulker/p78638

I use handled straight edges (taping knives) to push the paper down to the skirting/ceiling and run knife along the straight edge to cut away the excess.

https://www.screwfix.com/p/marshalltown-taping-knife-10-254mm/48250 a less wide one might be better though if the walls are slightly out of straight. Cheaper brands are available.

https://paintshack.co.uk/products/olfa-japanese-steel-snap-off-9mm-knife The black OLFA blades are the sharpest I have come across. Just snap the end off as it becomes blunt. I normally extend the blade by about 4cm so that it can flex against the straight edge and pull it at about 15 degrees to the skirting. If you apply too much pressure, the blade will snap. Retract the blade after each cut, if you don't, you increase the risk of cutting yourself. The Olfa knife in the first image is my favourite 9mm blade knife. I have used about 7 different brands over the years.

Best of luck

 

[lc155]

Hi mate, cheers for responding.

You didn't need to seal the old lining paper but doing so isn't a bad thing. When papering over old lining paper, you can find that the adhesive reactivates the old paper's glue, causing it to bubble. Most of the time the bubble shrinks back as the new paper dries but it can be a bit of a pain it it happens over a join in the new paper. Given that you have applied the Guardz, you shouldn't have that problem.

When I would wipe the lining down or when peeling the backing off, it was fairly obvious that the old flake paste was reactivating. I didn't want that weaker adhesive interfering with the wallrock adhesive, so sealing it and essentially making the lining paper a fresh bare wall (instead of taking it off and wishing I'd never started after looking at the condition of the plaster) seemed like the best option to go for.

One thing I didn't mention in the OP is that one of the walls (the exterior one with a boarded up chimney) I did strip to the bare plaster, as it had polystyrene on the bottom layer, making it easy to scrape the whole thing off in minutes. I plan to replace the crappy polystyrene with some of that chunky wallrock thermal liner, since that wall always got colder due to the chimney.

So I got a taste of how the plaster condition is there. Let's just say that I did a lot of scraping out of cracks, knocking loose surface chunks of plaster off, and then slapping on a lot of Toupret TX 110 to bring the wall back to a decent condition. Most of it was probably unnecessary since the thermal liner will be the new base wall (and will be flat!), but I didn't want to risk the weight of the liner pulling anything loose and it coming down later on. Also, I'm a bit of a perfectionist and hate doing things half-assed. Lots of bodges in this house over the years, and they get annoying to find, so I don't want to contribute.

Assuming that you have a decent brand of matt emulsion, I would just paint straight on to the ceiling. I would only have concerns if it were a shower room ceiling and subject to very high levels of humidity. And were it so, I would have recommended water based eggshell anyway.

I have not yet decided on the emulsion I am using. Once I'm done with sealing the walls I'll look into painting the ceiling. Any recommendations? Just a high quality white one will do. The ceiling is fairly low (and touchable for adults) but I don't imagine that's much of a big deal.

Having used the Guardz, you will find that the water in the wallpaper will take longer to evaporate as it can only evaporate in to the room (rather than some soaking in to the wall). It will not affect the adhesion.

That's fine, long as it sticks and seams don't show, and paint goes on well, then I'm happy.

I don't know how much experience you have of working with lining paper but I would suggest you consider using a roller to apply the paste rather than a brush and use a "caulking blade" to smooth the paper.

No experience! Doing this all for the first time, I just sit down and do weeks of reading before I get to it, so at least I generally know what I'm doing, it's just my lack of experience that slows me down.

I'll be putting up a paintable wallpaper, something like a superfressco. So while I had read that rolling the paste on was the best way to go, I'm not sure about a caulking blade to smooth the paper, feel like I might mark the pattern. Was looking at maybe something in plastic in combination with those smoothing brushes?

I use handled straight edges (taping knives) to push the paper down to the skirting/ceiling and run knife along the straight edge to cut away the excess.

Ah perfect, I was actually using one of these to smooth the filler over a large area of plaster I had to fill in on that aforementioned wall, so I can use it for this too.

I think I might need a longer blade (wallpaper width) for the ceiling though. This room has walls that curve halfway up, so there's no distinct edge between wall and ceiling, so I'll have to cut the paper up there very carefully with a long straight edge.

The black OLFA blades are the sharpest I have come across. Just snap the end off as it becomes blunt. I normally extend the blade by about 4cm so that it can flex against the straight edge and pull it at about 15 degrees to the skirting. If you apply too much pressure, the blade will snap. Retract the blade after each cut, if you don't, you increase the risk of cutting yourself. The Olfa knife in the first image is my favourite 9mm blade knife. I have used about 7 different brands over the years.

I actually use an OLFA knife (the A-1 shell slim one) with the black blades already, so I'm sorted there! Cheers for the tips at cutting it with a nice clean edge. Maybe a larger shell would be better?

 

[opps]

Tx110 is a good filler. Personally, I prefer using Toupret fillers more than fillers like the Gyproc Easi-Fill. Easy-Fill is very soft but it is significantly cheaper, which is why a lot of decorators use it.

I have never seen lining paper pull walls down. I have seen lots of walls though that have been held together by the lining paper. That is often more the case with old lathe and plaster ceilings, if you attempt to strip away the old lining paper they may well fall down.

That said, don't forget that the TX110 will be more porous than the previously coated areas of plaster. That porosity is generally referred as "suction", namely the TX110 will suck more water out of the wallpaper paste if not "primed" (be it with dilute paste or another product).

A roller will be fine to apply the paste on a blown vinyl so long as you are not too aggressive. Do not let the paste soak in and then forget about it and roll again, you might crush it. Consider the Purdy Colossus sleeves. It will cost you £7(?) for the sleeve, but once washed out, you can paint with it.

Do not use the vinyl smoother for the blown paper. Buy a wall paper smoothing brush.

I have no idea how heavy(/deep) the blown/embossed pattern is. The knife/straight edge should be ok for something that is a couple of mm thick. In the real world you will be caulking the edge anyway if it is paintable. IMO, the straight edge is easier than a pencil and scissors. It also has the advantage of not having to pull the paper back of the wall to then cut it (which might, or might not upset the base paper).

Spend a quid or two on a sponge to wipe away the excess paste. When using flat papers I use a cloth (pub bar towels are great, but you don't want to crush the finish. Have a bucket of warm water just for the sponge. You don't want to inadvertently move paste around the paper.

The longer a straight edge, the more likely you are to push the blade against a void, and the more likely you are to rip the paper. Less is more, but slower.

Olfa- I stick with the 9mm blades because they flex. Flexing increases the risk of the blade snapping but I am am using it to cut a very thin product, if I were cutting carpet I would consider a taller blade.

I have just finished work and am having a quick pint, if I failed to address anything, please do post back.

 

[lc155]

Tx110 is a good filler. Personally, I prefer using Toupret fillers more than fillers like the Gyproc Easi-Fill. Easy-Fill is very soft but it is significantly cheaper, which is why a lot of decorators use it.

Yeah, I'd read up on Toupret and like what I see from using it so far. Dries to a nice rock hard cement. Dunno how well it will take to re-drilling as it claims though. Maybe I'm just not experienced enough at filling screw holes all the way to the back. Always feels like I just coated the surface of the hole rather than get it all the way to the back of the plaster, and it would be too weak to reuse or drill against later on.

I have never seen lining paper pull walls down. I have seen lots of walls though that have been held together by the lining paper. That is often more the case with old lathe and plaster ceilings, if you attempt to strip away the old lining paper they may well fall down.

Fair enough. The thermal liner I mentioned for that wall is 4mm thick, the KV600. Was just concerned about the amount of weight on the wall, as I'll then have to line over that, so I can put over the paper (as it will be an expanding one which the thermal liner can't take directly on top).

Funnily enough, the ceiling in this room has old textured paintable wallpaper on it, that's what I plan on repainting. No idea how old it is, but there's no chance I'm pulling it down because I bet the ceiling's coming down if I do.

A roller will be fine to apply the paste on a blown vinyl so long as you are not too aggressive. Do not let the paste soak in and then forget about it and roll again, you might crush it. Consider the Purdy Colossus sleeves. It will cost you £7(?) for the sleeve, but once washed out, you can paint with it.

Gotcha. For painting (and currently for rolling Gardz on), I've been using the Hamilton Perfection medium pile microfibre sleeves, as they seemed to be very highly rated. They sure do suck up a load and dump it all at once though.

That said, don't forget that the TX110 will be more porous than the previously coated areas of plaster. That porosity is generally referred as "suction", namely the TX110 will suck more water out of the wallpaper paste if not "primed" (be it with dilute paste or another product).

I had planned to Gardz this bare wall as well once I was done with filling to seal it all in (there's some very old paint on it, etc), so I'd accounted for the porosity already.

I have no idea how heavy(/deep) the blown/embossed pattern is. The knife/straight edge should be ok for something that is a couple of mm thick. In the real world you will be caulking the edge anyway if it is paintable. IMO, the straight edge is easier than a pencil and scissors. It also has the advantage of not having to pull the paper back of the wall to then cut it (which might, or might not upset the base paper).

I'm after something that isn't too aggressive and 'Grandma's house' like, so I had been thinking about the 'Greek Key' superfressco from Graham & Brown. Ever worked with that one? Based on the samples it is a very lightly textured one.

Spend a quid or two on a sponge to wipe away the excess paste. When using flat papers I use a cloth (pub bar towels are great, but you don't want to crush the finish. Have a bucket of warm water just for the sponge. You don't want to inadvertently move paste around the paper.

Gotcha, I'd bought a pack of sponges in the event I needed them so I'm covered.