Removal of Oil based glaze

[cocoots100]

Hi
Can someone advise on the options available to decorate over a wall which has had a paint effect which has been sealed with an oil based glaze.
Basically the wall has had a paint effect similar to the orange peel textured effect you get when emulsion is applied with a long haired roller. I think it is a stippled faux animal skin type effect. This is sealed with what looks and feels like an oil based glaze. I think there is also a top coat of oil based varnish to add to the mix as when it is rubbed down (as there is a slight texture to it) it becomes as smooth as a plastic coating.

Basically either an emulsion or wallpaper paste will be sitting on this coating. However if emulsion goes on top of this will it crack as the surface is too shiny to take the paint? If wallpaper paste sits on top of this will there be mould problems later on?

Any help would be greatly appreciated.

 

[Nestor_Kelebay]

This "oil based glaze" can be considered an oil based paint regardless of whether it's a drying oil (like Tung Oil) a true varnish or a polyurethane "varnish". All of these different coatings are similar enough that they can just be considered an oil based paint for recoating purposes.

So, what you have is an oil based something on the wall with a texture to it.

The first step, if you want a flat wall, it to either remove that texture by scraping the high points off, or fill in the low spots by skim coating the wall.

To get anything to stick well to a smooth surface, you need to roughen it's surface, and you could do that by using a chemical deglosser like "Liquid Sandpaper" (if it's available in your area).

Probably what would be best is for you to try scraping the texture down flat and try using a chemical deglosser to roughen the surface of the glaze so that any skim coat of plaster will stick better to it, and then decide what method you want to use, and then post back once you've got a flat wall on how to proceed from there.

If it were me, I'd probably use the chemical deglosser to roughen the surface of the glaze, then paint that surface with diluted wood glue and allow that to dry, and then skim coat over the surface with a plasterboard joint compound. The PVA glue would help bond the plaster to the oil based substrate.

And, of course, once you have a flat smooth wall with plasterboard joint compound on it, prime and paint as usual.

aside:
(drying oils (like Tung Oil or boiled linseed oil), alkyd paints, true varnishes and polyurethane "varnishes" are all so chemically similar that they can all be treated as "oil based paint" for recoating purposes. same goes for floors; a polyurethane hardwood floor finish can be considered an oil based floor paint without any pigments in it to give it color or opacity. the only time you gotta watch out is if you have the true floor "waxes" that they used on hardwood floors prior to polyurethane coming on the scene in 1956. those old waxes were made from something called Carnauba Wax, and there are problems covering those old waxes with a modern polyurethane floor finishes. even if you think you're removed all the old Carnauba Wax from the wood, the wax that has penetrated into the wood can still cause problems for a subsequent coat of polyurethane hardwood floor finish.)

 

[cocoots100]

Nestor
Thanks for the reply, very informative.
I think in this case the texture is not very pronounced for any scraping or filling of the gaps. We try to avoid the re-skimming of the walls if possible.

How would this work?
Rub down the walls with 120 grade abrasive.
One coat of PVA diluted 5:1
two coats of emulsion.

Would the PVA be neccessary if you have already rubbed the walls down? As we are treating this as with any other oil based surface, I'm just thinking about the procedure on painting emulsion on an oil based gloss surface - would the same, in theory, apply here.
Cheers

 

[Zampa]

That sounds more like a dulux paint effect called...........(ive forgotten sorry)...are you sure its an oil based glaze?...the characteristics being fast yellowing and quite a sheen.

Give the wall a really good sanding down with 100 grade aluminium oxide paper.

Then re decorate...if its going to be papered then id suggest lining it first to increase the amount of absorbtion...giving the paer something to grip to.

If your emulsioning it then again a good rub down and then a slightly thinned coat of dulux supergrip primer..this should provide a barrier caot and allow you to paint yuor emulsion over the top.

You could also use oil based primer sealer...but it isnt user or environmetal friendly...i.e...it will stink the house out!

 

[confidentincompetent]

That sounds more like a dulux paint effect called...........(ive forgotten sorry).!

Duet (you havin grey moments like me steve).

Cocoots, if it is a modern house probably like zampa says, acrylic varnish is normally used here. I've found in tha past that a quick rub down and coat up with emulsion is fine. Dont use pva here as wall is already sealed. Though if your hanging paper, lining might be best as zampa mentiond, otherwise paper will take ages to dry out.

 

[Zampa]

Thats it!!......crap stuff, dulux answer to rag rolling...it was never going to take off...to hard for for your average DIY'er...and 35 quid a tin for the basecoat...topcoat and sealer...to expensive too....and too amutuer for the seasoned pro.

Plus it always looked like somone had knocked a dirty roller out on the wall....ok with pastels but horrendous with strong colours.

I knew that drinking white spirit would rot my brain cells one day!

 

[confidentincompetent]

Thats it!!......rubbish stuff, dulux answer to rag rolling...it was never going to take off...to hard for for your average DIY'er...and 35 quid a tin for the basecoat...topcoat and sealer...to expensive too....and too amutuer for the seasoned pro.

Plus it always looked like somone had knocked a dirty roller out on the wall....ok with pastels but horrendous with strong colours.

I knew that drinking white spirit would rot my brain cells one day!

Yeah, and once started had to go like ****e no pausing or edge was gone

 

[Nestor_Kelebay]

Cocoots100:

If you sand the walls down, then you make them rough enough for any paint to stick to it well.

The only thing is that if the existing surface is oil based and you want to paint with an emulsion, I'm a big queezy about how well that emulsion would stick to an oil based paint despite it being sanded.

So, once you sand it down, do this:

Use a Q-tip to paint some of your emulsion onto a sanded area and allow it to dry. The following day, scratch at it with a sharp paint scraper and see if you can scrape it down without it breaking free of the oil based paint in large flat "chips" (indicating that the emulsion paint is sticking to itself better than it's sticking to the oil based substrate).

If the emulsion paint breaks off in chips when you scrape at it, then I'd prime with an oil based primer first, then paint over the oil based primer with your emulsion paint.

If you can scrape the emulsion down without it breaking off the oil based substrate in "chips", then the adhesion of the emulsion to the substrate is not the weakest link in the chain, and I'd just go ahead and paint over the roughened oil based substrate with the emulsion paint.

How many coats you need to hide the color of the substrate depends mostly on the gloss and color of the paint you put on. It can be anywhere from 1 to 6 or even more.