Painting walls after water damage

[Nearlyhadenough]

I had a bath tap leakage recently and need to repaint the walls of the room below.

What can I do to help make sure the paint covers the watermarks? There isn't too much and its had plenty of time to dry out.

I think you go over them with a thinned PVA glue first and then paint as normal.

Use a stain blocking paint or primer. Make sure you have given the damp area plenty of time to dry out before you get painting.

Thanks, now you've mentioned it I think I've heard about glue before.

I'll have a look in the DIY shop for some primer- the area has had about 6 months to dry and it wasn't a huge leak.

Please don't put glue on anything you hope one day to paint.

Stain blocker is what you need. It's like white undercoat. Any paint shop or DIY supplier has it. Start with a 2.5 litre tub.

Don't use the spray cans, they are expensive and will go everywhere.

just checked, it is more expensive than I remembered. Maybe start with a 1-litre can? But don't be stingy with it.

www.diy.com/search/results/?question=stain+blocker&prodNum=7&fromUtil=true&fromFacetForm=false&searchMode=and&sortOption=priceIncVat-descending-numprop&pageSize=7

www.wickes.co.uk/Wickes-Trade-Stain-Block-1L/p/121755
and you will need white spirit to clean up, it dried quite quickly and is difficult to get off.

Wilko have a water based own-brand which is cheaper.

Annoyingly, whichever brand you look at, there is always a reviewer saying it doesn't work.

My instinct was to say "buy Dulux Trade and hang the expense" but now I don't know. Some decorators like Zinnser BIN or 123 plus but I have never used them.

I've used Polycell Stain Stop successfully and a little goes a long way. It is nigh on impossible to apply with a brush due to the viscous texture. I found it easiest with a small gloss paint roller. This also gave much better result over trying to use a brush.

Thank you very much!

This is the bank holiday weekend job for me now!

Our decorator used Zinnser and no marks have come back through. Think he bought it from the Johnsons trade shop