Primer for old wood doors with old varnish coming through paint

[pftw]

Have a 1930s ish house with original wooden doors.

Stripped one of them previously. Didn't do it that thoroughly - light wet sand at the end only - because I'm sure there is lead based paint there and I was worried about making dust. There was definitely some old varnish left at the end. I repainted with a cheap primer then dulux satinwood.

As you can see from the photo, either the old varnish is leeching through, or possibly sap from the wood? Think the doors are pitch pine.

Have one door which is going off to be stripped properly, and want to put some more paint on this one to cover it up.

Can anyone advise on a suitable product, ideally a primer to stop this coming through again? Ideally something available at B&Q or screwfix...

Thanks,

 

[JohnD]

Hot air gun, outdoors or using an extractor.

I don't believe varnish contains lead

If you suspect something, send a chip off for testing or get a home test kit.

 

[pftw]

Thanks. This door is only thinly painted and apart from the staining is in good condition. I was hoping I could just overpaint this one.

The other door is going off to be stripped by a local company. Not prepared to deal with the lead-based paint stress again!

Mainly looking for recommendations on a primer or undercoat which I can use to stop the staining happening again.

Zinsser B-I-N looks like it might do the trick?

 

[opps]

I am guessing that you are using waterbased paints. BIN or oil based undercoat should be fine.

BIN is more expensive but will dry much faster. It is however difficult to get a flat finish because of the speed with which it dries.

Oil based undercoat will be easier to apply, but you will have to wait a few days before you overcoat it with the waterbased finish. If you overcoat it too soon, you will get fisheyes in the finish.

 

[sparkwright]

Another vote for oil-based undercoat.

 

[richw]

BIN is brilliant. I overpainted some previously stained 1960s doors and then applied white eggshell. You would never know they used to be dark. Used a 1.5" brush and a 6" foam roller.

Problem with BIN is that it's evil to work with. The consistency of milk. Dries in about 20 minutes, so you have to work very quickly. Doesn't come off anything at all - so bin anything on which you spill excess. And bin the brushes/rollers too.

 

[Wayners]

Clean spirit will clean BIN out of brushes if you leave in for 48h.
Then wash out with water.
Foam roller to apply. Doors are flat so easy enough

 

[opps]

BIN is brilliant. I overpainted some previously stained 1960s doors and then applied white eggshell. You would never know they used to be dark. Used a 1.5" brush and a 6" foam roller.

Problem with BIN is that it's evil to work with. The consistency of milk. Dries in about 20 minutes, so you have to work very quickly. Doesn't come off anything at all - so bin anything on which you spill excess. And bin the brushes/rollers too.

You were lucky that the rollers didn't become floppy. The first time that I tried to use BIN with a roller, I used a small foam roller. After about an hour, it had almost doubled in length and height and became incredibly floppy.

I now use mohair type rollers.

Brushes- yeah, I used to use cheap brushes but it is impossible to get a decent finish with with a cheap brush. Zinsser recommend using meths to clean brushes. IMO, all is does is dilute the residue on the brush.

Elsewhere on the web, I discovered that you can use household ammonia to thoroughly clean your brushes. BIN is pigmented shellac suspended in alcohol. Alcohol is slightly acidic. Household ammonia is an alkaline. I am not a chemist but I can confirm that a recently used brush can be cleaned in water after spending a minute in household ammonia. Brushes than have gone hard can be left overnight in the ammonia, again they will be as good as new- leave the tub of ammonia outside overnight because of the fumes. In the morning the ammonia will have evaporated off and the tub will contain water and white powder (which can be poured down the sink).

Ammonia can also be used to clean up any spillages.

BTW, the household ammonia works out far cheaper than meths, and works much better, but the former smells.

 

[richw]

I'll have to try ammonia. I did buy some expensive BIN brush cleaner, but found it didn't work very well on the brushes (excellent on your hands, though). Funnily enough, I also used a foam roller - didn't have any issues with it deforming.

For undercoat or top coats, yes, absolutely, you want nice brushes. I was enjoying the Kana ones, but they've stopped doing them. The cheapo brushes are was nastier, but I don't mind binning them after a session with the BIN. I find the finish is good enough for a primer coating.

 

[DiyNutJob]

I was hoping I could just overpaint this one.

Why is hope needed? Paint is to cover. If it doesn't cover, stir the paint and cover again. No laws says you can't give it 100 coats. If the paint is that bad to need so many coats, get something else. Most modern primers are primer undercoat in one. Even cheap primer will cover well. In fact cheap primers have larger "particles" that will cover better than smooth expensive primers.

 

[hants jobber]

Clean spirit will clean BIN out of brushes if you leave in for 48h.
Then wash out with water.
Foam roller to apply. Doors are flat so easy enough

When i use bin i clean brushes out with thick household bleach, works every time and all houses have it so can use customers.

 

[opps]

I'll have to try ammonia. I did buy some expensive BIN brush cleaner

I once purchased that as well. I too was not impressed with it.

 

[opps]

When i use bin i clean brushes out with thick household bleach, works every time and all houses have it so can use customers.

Good call. I have never tried it but bleach is also alkaline.

 

[pftw]

Thank you all.

Went with the BIN in the end. Two coats of that, then two of Dulux Satinwood. Still a bit of staining on the worse side which needed an additional Satinwood coat, but that got everything covered. Everything looks (and smells) much better now.

The BIN did dry very fast but that was actually quite helpful as I was time limited. Meths worked well to clean spillage and brushes etc, but got everything sorted before it had dried.