The best paint to cover and block a stain
There are several different stain blocking products on the market which are all good in a different ways, or for blocking and covering up different types of stain. I’ll take you through the main paints in this article, which will help you make the right choice. You can research each product on the Decorators Forum UK.
Generic Waterbased stain blocks
Each of the main paint manufacturers have their own water-based version of stain block. These are quite simply labeled “stain block” and are by far the easiest option, however, may not be as effective on harder stains. This doesn’t mean they don’t have their uses; a ceiling which is affected by nicotine from cigarette smoke for example. Just don’t expect miracles, any heavy stains need to be dealt with by something a bit more robust.
Stain block and Finish Coat in One
As paint technology is advancing, we now have all these new “all-in-one” products that are really quite impressive. Johnstone’s StainAway is a white, durable matt emulsion which blocks out stains quite affectively and leaves a nice finish, eliminating the need for more than one product. This product works well on pretty much any type of stain, except maybe water marks. It is important to leave the first coat for at least 4 hours before applying your second.
Another fine example of this is Zinsser Perma White. Again, it will block out mild stains, doubles up as an emulsion and has mold inhibitors, meaning it will combat mould and mildew growth in the future. It is the perfect product for a bathroom or kitchen.
The other advantage is Zinsser Perma White is durable enough to use on ceilings, walls and woodwork and it can also be tinted. Note, this product will not block a stain as effectively as some of the products listed below, but if you want longevity in a room susceptible to mold growth then this is the product for you.
Oil-Based Stain Blocks
Now we are talking!! These products are the most effective at blocking and covering stains such as grease, water marks, heavy nicotine and graffiti. Just make sure if you are applying it inside over a large area, you keep your work area nice and ventilated. Otherwise the fumes are a bit much. Look out for Zinsser CoverStain, or any oil-based undercoat. I personally feel these work best. You can buy coverstain from loads of trade outlets but unless you have a trade account it may be better to purchase it online.
Shellac Based Stain Block
Shellac products have most of the advantages of oil-based, but with the added bonus of rapid drying. The most well known is Zinsser BIN, however there are now many brands offering similar products. Coo-Var’s version is called Shellac Prime All. Smith and Roger do a version called Blockade. They all pretty much do the same job and they’re great for blocking or covering small stains before coating up with emulsion.
What do Other Decorators Think?
I do like coverstain in a spray can for small areas. I’ve always got one in the van in case I have any stain bleeds.
The cheapest and best way to cover and block a stain has always been oil-based undercoat. All you need to do is loosen up the product with some white spirit, double roll, leave to cure and you’re good to go. Shellac is good, but it can lead to adhesion issues between stain block an emulsion if you’re not careful.
If drying time is an issue then use BIN, however often it dries as an amber colour. If drying time isn’t an issue and you never want a call back for a stain then use oil undercoat, any will do. Never fails and dries white. Coo-Var also has a good product which is a stain block and finish in one. Perfect for a small ceiling. Johnstone’s Stainaway is good, however I have seen it fail a few times in other people’s experiences.
I’ve used Johnstone’s damp proof paint for years. Its got a great flow rate. And nothing comes through it. Its oil based but dries super quick, so you can over paint the same day. The downside is, it stinks to high heaven.
Depends on want the stain is. For water mark or if just a small stain normal use bin as well hold it back quick drying time. For large water stain again a Zinsser product, coverstain primer sealer .
Smith and Rodger blockade
Of you have the time, oil undercoat will beat any fancy Zinsser product