It's not distemper - but what is it?

[frenchian]

I've got a 1930s house that I've owned since the late 80s - when I first bought it the bathroom was "surprising" - bright (very bright) mustard coloured walls with a "chocolate" bathroom suite. So nice that it had to go and quick!
The mustard walls were almost gloss finished, so I sanded them lightly and emulsioned them. All was well - for about a year or so when small chips of the emulsion started to flake off. So I sanded/repaired those bits, some of which worked, some needed reworking. Over the years large parts of the walls have been stable, some bits have been redone several times over - generally each time we've repainted the entire bathroom.
This year we've decided to try to do a more permanent job, I've removed all loose top coat by scraping aggressively - on one wall this has led to around 3/4 of the paint coming off in chips, back to that lovely mustard colour again.
So what is this original paint finish, and what do I need to do to cover it once and for all?
The symptoms are like distemper - but it's gloss-like and doesn't have any chalky feel to it at all. Any good ideas how to solve this 25-year old problem please?!

Thanks, Ian

 

[opps]

It does sound more like a condensation- lack of airflow issue, than anything else.

If they had used oil based paints, even though you had the sense to sand them, and the problem is related to cold external walls, then sadly you are on a hiding to nothing, unless you deal with either insulation or airflow.

 

[Bosswhite]

Wet your finger, then rub the paintwork if it comes off on your finger its distemper !
A coat of stabilising solution will sort it out

 

[frenchian]

I did wonder about that - I've just installed an automatic extractor and am improving the heating in case that's the cause.
I sanded all of the wall in question 2 weeks ago, I got all the edges between the old and new paint nice and smooth, the left it - today about 10% of the feather-edges had begun to lift slightly - so yet more sanding needed.
If it is an oil-based paint, are there any recommended primers I can try?
Thanks, Ian

 

[opps]

Assuming that the room has 4 walls. Is the problem isolated to the external walls?

 

[frenchian]

The 2 outside walls have definitely been the worst.

 

[opps]

I have seen ambient moisture in WCs result in mold going through3 layers of painted lining paper. Typically, in those cases I would start by increasing airflow and then consider dot n dab plasterer board but I appreciate that might not be an option. In the interim period, given that you have tried to fix things, you could try a less porous paint such as water based eggshell and see how that goes. It will become slightly softer if there is a lot of heated water vapour clinging to the wall.

 

[opps]

Sorry I meant to say foam backed pasterboard.

 

[opps]

The 2 outside walls have definitely been the worst.

The automatic fan- is it one with a humidistat? They definitely help.

 

[JohnD]

If it is glossy it might be old linseed oil paint. If so it comes off easily with a hot air gun and wide metal scraper. You may need sandpaper on the burnt scraps after.

Need some kind of mask and wash skin and hair after due to lead content.

 

[frenchian]

There's no mould present (and the bathroom has never suffered from it), it's interesting that the paint always chips back to the mustard coloured surface. I'm convinced that it's this paint surface that is the root cause of the problem, maybe exacerbated by the fact that it's in a damp environment.
I've never come across linseed oil based paint on walls before (and a quick search hasn't brought up anything), is there anyway of positively identifying it and is removal the only solution?
Thanks to all for your suggestions, Ian

 

[opps]

There's no mould present (and the bathroom has never suffered from it), it's interesting that the paint always chips back to the mustard coloured surface. I'm convinced that it's this paint surface that is the root cause of the problem, maybe exacerbated by the fact that it's in a damp environment.
I've never come across linseed oil based paint on walls before (and a quick search hasn't brought up anything), is there anyway of positively identifying it and is removal the only solution?
Thanks to all for your suggestions, Ian

There once was a habit of adding varnish to paints. I have often seen woodwork paint chip down to this level and not further. In your case you have already sanded the areas so poor adhesion is less likely to be the issue. I still thing that humidity is making the situation worse. The following post might help explain things in more detail.

[url]//www.diynot.com/forums/viewtopic.php?t=45518 [/url] scroll down to the first post by nesto-kelebay