28/10/2026
What's the best stain block for water marks?
You’ll get different answers depending on who you ask. Even professional decorators are split.
A lot of professionals use oil-based undercoat or pliolite-based masonry paint. These work well, but they smell and take a long time to dry. There are a lot of modern paints that work and are less hassle.
Water-based stain blocks as effective, but they’re more pleasant to use. They’re great for minor staining and would cope with this, but you might want to go for something a bit more substantial for heavy staining. Fiddes Full Stop H2O is probably the best water-based version I’ve used.
Shellac-based stain blocks like HB42 PS1, Smith & Rodger Blockade, Zinsser BIN and Fiddes Full Stop are quick-drying and work very well.
Oil-based stain blocks like Zinsser Cover Stain and HB42 PS2 also work well.
Then there are products that act as a stain block and finish coat in one, like Johnstone's StainAway and Dulux Trade Stain Block Matt. I haven’t used these in a while, but I know other decorators do.
You can buy everything you need from online suppliers like Next Day Paint, Decorating Centre Online, and The Paint Shed.
Some of the brands mentioned sponsor the page, but recommendations, as always, are my own.