What filler can I use over plastic cable ducting?

[patagonia]

My handyman is decorating a small bedroom for me. It had wallpaper on the lower half of the walls, finished with a border, all of which was stripped off. The area which had been papered was rubbed down with sandpaper, washed down and filled as necessary, filler rubbed down with fine sandpaper. A mist coat was then applied (I am not sure whether he applied this to the whole wall or just the filled areas). When the first coat of full strength emulsion was applied, some bubbles appeared, which have now been sanded down. One bubble was elongated and when he rubbed it down he exposed some plastic cable ducting which was very close (only 2mm) to the surface. What can be used to fill this gap which is about 4 inches long and an inch or so wide? He has rubbed it with coarse sandpaper to give it a key but what will stick to plastic and provide a smooth finish which will blend in to the surrounding plaster?

 

[opps]

Light weight fillers such as Toupret RedLite or RedDevil OneTime will adhere to the ducting. Those areas will always be "fragile" though.

You mention bubbles appearing and that they were sanded back- I don't quite follow. What bubbled? Plaster shouldn't bubble however a skim coat of plaster applied over wallpaper may bubble but typically it would crack (requiring a refill).

Without knowing what state your walls are in, as a professional decorator, I am inclined to recommend that you coat the problem areas with a coating that will prevent the water in the emulsion from affecting the substrate. The cheapest option would be a couple of coats of cheap oil based undercoat. The better option would be to use something like Zinsser BIN. It is alcohol based and dries very quickly, it isn't cheap though.

 

[patagonia]

Many thanks. It wasn't the plaster which had bubbled in most cases; it was the paint, which suggests that he either hadn't sanded, dusted or washed down sufficiently well after removing the wallpaper and in particular the boarder or mist coated where he had done filling or had applied too thick a coat or 2nd coat too soon over the problem areas. When he rubbed down or scraped off the elongated bubble which one could feel was not in contact with the wall, he found that there was plastic trunking close to the surface which must have been just skimmed over before painting and later papering. I don't want to paper, just emulsion, so I need it to be filled correctly so it is not obvious that it has been filled and I need the filler to stick. Perhaps this is why there was paper on the lower half of the walls! It has annoyed me ever since I moved in because you could see adhesive smears on the painted wall above the wallpaper boarder.

Incidentally, the paint bubbles had mostly sunk back by the time the paint had dried.

 

[Chud]

OK a couple of ideas:
Use a two part filler such as isopon p38 (car body filler) or ronseal high performance wood filler
https://www.google.com/search?q=ron...DigB&biw=1520&bih=476#spd=9981913150508818031

Those should stick well to the plaster and the plastic and be tough enough. you may need to smear the surface with some lightweight filler or gyproc easi fill before re-painting.

Alternatively you could use a caulk type product such as the nemesis caulk sold at screwfix or geocel painters mate but I suspect that will always be noticeably different to the rest of the wall and neither can be sanded so need to be got right at time of application.

 

[opps]

OK a couple of ideas:
Use a two part filler such as isopon p38 (car body filler) or ronseal high performance wood filler
https://www.google.com/search?q=ron...DigB&biw=1520&bih=476#spd=9981913150508818031

Those should stick well to the plaster and the plastic and be tough enough. you may need to smear the surface with some lightweight filler or gyproc easi fill before re-painting.

Alternatively you could use a caulk type product such as the nemesis caulk sold at screwfix or geocel painters mate but I suspect that will always be noticeably different to the rest of the wall and neither can be sanded so need to be got right at time of application.

I see where you are going with the two pack filler but sanding them flat requires quite a bit of pressure and there is the risk of the trunking flexing and cracking the filler, however you are correct that it will stick to the plastic.

Caulks tend to be waterbased and thus shrink. You'd have to wait a few days for the caulk to shrink before overfilling.

 

[opps]

I don't want to paper, just emulsion,

Lining paper will provide you with a uniform canvas. If the walls had been painted previously (prior to the boarder and wallpaper) it can be difficult to fill/sand and replicate the existing orange peel effect. Sometimes stippling the newly sanded areas with a brush works sufficiently but if the orange peel is very pronounced you are a hiding to nothing.

Another advantage of lining paper is that it helps to hide any minor cracks that may eventually appear (eg. over the trunking).

And no, I do not have shares in Lining Paper Ltd.

Sorry, I am not trying to coerce you into spending more money than you need to, but, in my professional opinion, lining the walls will give you a better finish.

 

[patagonia]

Thanks, all. Difficult to know what to try for the best. Opps is probably right but things have gone too far for that. The other walls are finished and looking good and the problem one has had the first coat so I'd like to take a chance on filling this gap over the trunking and see if we can achieve an adequately matched finish before doing any relining. The room may never be used (2 spare bedrooms and no visitors) but I need to get it freshened up after installing new windows so that the house is in a fit state to sell when I can't continue here on my own which may not be for a couple of years. If the filling and overpainting doesn't look right, I'll consider relining at that point but I presume that would mean relining the whole room so virtually starting the decoration from scratch and I have already spent several hundred pounds on time and materials.

 

[opps]

Fair enough and good luck.

BTW it would only take about 2 hours to line one wall and it shouldn't be necessary to line the other walls.