Wallpapering

Jimmy2Coats · Post by **Jimmy2Coats** » Tue Jun 21, 2022 8:57 pm

Hello everyone, I'm new to the forum so go easy on me lol. I'm a reasonably experienced decorator but just looking to see if there's varying opinions to this problem. Last year I wallpapered a woman feature wall in her extension. I mist coated in contract and emulsioned all walls except feature wall in vinyl. I x lined the FW but I'm not 100% sure if I sized first but I normally do. I applied the wallpaper and it looked great one of the best I've done. However about 6 months later she asked me to have a look at it as on various areas it had come away from the wall and hadn't adhered. The paper was stuck to the lining but the lining not to the wall. I cut through it in several places and syringed paste behind it. That was ok for another while but its happened again and its worse. Any ideas where I went wrong ? I'm going to strip it and re- do it.
Jimmy2Coats

Puma · Post by **Puma** » Wed Jun 22, 2022 4:09 pm

Presumably the paper has pulled off the contract matt?

I find the thinning instructions can be incorrect on contract matt's, and that they sit on the plaster instead of being thin enough to seep into it and achieving proper adhesion. Otherwise maybe the plaster was polished a little?

Anyhow sorry to hear of your troubles and good on ya for fixing it for the client.

I always use a fiber liner, which generally gives lots less bother imo.

Jimmy2Coats · Post by **Jimmy2Coats** » Wed Jun 22, 2022 5:48 pm

Thanks for that much appreciated. When I strip the paper and lining paper should I give the wall a coat of Johnstones primer sealer or something similar before I cross line and wallpaper? I'm thinking that would give it a good sound surface and seal the porus plaster?

Puma · Post by **Puma** » Wed Jun 22, 2022 6:42 pm

I think you are going to have to go in expecting to have to sand or scrape the contract matt off to be sure. Then you will be back to bare plaster - check it is sound, there is an outside chance that an skim plaster which is past its sell by date has been used and it simply isn't up to the job.

Then in my book, with bare plaster, I always paste the wall and paste the paper. I usually use the wall paper primers over mixed old paint / fillers or old wallpaper etc Other folk might differ on that one.

dynamod · Post by **dynamod** » Thu Jun 23, 2022 8:23 am

Contact Matt will just suck the water content of the paste straight back, leading to poor adhesion and eventual failure.

If the mist coat comes off ( if it's at a suitable dilution it shouldn't) I'd seal the wall with a thinned version of whatever paste you end up using for the lining/finish papers.

Zinnser Peel Stop seems an obvious product to recommend, but if the most coat is intact, thinned paste will be fine.

Jimmy2Coats · Post by **Jimmy2Coats** » Thu Jun 23, 2022 10:11 pm

I spoke to a painter I know well today met him in Dulux we had a good chat. I mentioned the problem. He said when I was emulsioning the other walls in the room with vinyl matt I should have just done the feature wall too as if it wasn't being wallpapered. Next day when i went to cross line it would have gave the paste a good sound surface to adhere to. Interested to see what yous think

dynamod · Post by **dynamod** » Fri Jun 24, 2022 6:03 am

I'd agree with what he said, but only up to a point. Any vinyl matt will be a better base for paper than contract mush, but that said I'd still be looking at a size coat of some sort and not relying on a paint to do the sizes' job. Dulux vinyl matt has lost a lot of its vinyl content over the last few years from what I've seen. Besides, it's an expensive way to seal walls (especially with Dulux prices these days) when flake paste, or even Beeline Black can be had at a fraction of the cost.

I miss the days of old glue size as it really was the best product for that job (but did it stink

), but thinned paste is still the best alternative. Zinsser Gardz at 50/50 dilution can and does work well, and for sizing it goes a long way. I was on an American paperhangers forum a while back and one guy was recommending full strength Gardz under every paper. I personally wouldn't recommend going that way, as Gardz leaves a particularly shiny surface, that once dry, weaker flake pastes (I'm thinking Laura Ashley) won't have the guts to prevent seam separation. The job of the size is to reduce porosity, not seal the surface completely. The paste on the paper still needs to absorb slightly to create a good bond.

To put it simply, I'd use a thinned out version of the paste being used for the main paper.

Jimmy2Coats · Post by **Jimmy2Coats** » Fri Jun 24, 2022 12:43 pm

Thanks for that pal. I normally always size before lining but I think on this job for some reason I didn't and I think that's where its failed. Or if I did it wasn't diluted properly. Anyway I'll be back to sort it soon and I'll get it right this time