"Wood stain is sucked out of the wood and mixes with the paint while wet, probably because this is a water based paint. Spirit based block is much better in my experience. Second and third coats improve the performance to provide an acceptable result."
"Had a stubborn stain left on a ceiling which has repeatedly returned from old soot staining where chimney was removed years ago. Two coats seems to have done the trick, I'm impressed as I've used other "named" sealers before and it's still leached through."
"Used this produce to cover nicotine stains on a buy to let we had just bought. Covered 90% of the stains in one coat. (10% of the ceiling showed slight yellow when coated with emulsion). We then re-coated the 10% with stain block and after another coat of emulsion it was all white. Also tried a more expensive branded product on a different ceiling and got a similar performance. I have little experience of stain blocks but I think that it is pretty difficult to keep the stain away which is why this product gets poorer reviews. I have used the aerosols in the past on small stains and found them very successful but would have cost a fortune to do all these ceilings with that product. If it is a small stain I would recommend the aerosol as an alternative however. You can apply more coats quickly with it. on a small area."
"Used this to cover coal dust and nicotine covered beams. Took two coats as the stain bleed through the first coat, does say on the tin that it can take up to two coats. I have used other oil based products that would have covered in one coat. I would say its a good product for light application but not for heavy cover."
"Went on fine - bit thick and consequently difficult to spread - but it's designed to block stains so not surprising its thick. Washed out from brushes very easily with water which is a surprise. Average value for money - seen similar products cheaper since. Not painted over yet as still not dry 3 hours later, so not yet able to rate this aspect but has a glossy finish so bit concerned."
"I've got no experience with similar products; only know that you can't cover old stains caused by leaks with normal emulsion or [as far as I'm aware] not even with oil based paint.
I did have to apply two coats to cover the stains, but I found it pleasant to work with and in the end it did the job.
Not sure what stains 'happygolucky' (review 8/5/12) was trying to cover, but I would happily buy this product again, just like other No Nonsense products I've used such as their decorator's caulk and powder filler."
"I had light stains on my paint work from condensation in a bathroom and I was surprised that I had to do two coats of stain block and to get an acceptable finish with my Crown paint. It would have been more of a problem if I had had worse staining or a larger area. Next time I would try something else."
"A broken chimney stack led to some sooty water penetrating the wall in my kitchen. After cleaning and allowing the area to dry thoroughly (two months) was concerned by a few small stained areas so used this paint prior to top coat.
Four coats later the brown stain is still coming through. As I don't want to top coat in brown I need to find another fix. I think the problem is that this paint is water-based.
I wish I had read all the feedback rather than the first page!"
"Got a tin of this to cover some marker pen marks and a dried water mark - after 4 coats of using this the marks were still coming through. Went to a local cheapy shop known for its good discounts, who had a brand named Stain Block for the same price - did the job in one coat. You could tell the difference immediately with the consistency of the paint itself."
"It took six coats to stop a water stain coming through the ceiling, even now I'm not sure its stopped. Not worth the money by any stretch of the imagination - don't bother with this rubbish - in fact i think I'll take it back"
"This product is a total waste of money. Used 5 coats on a tobacco stained ceiling and was totally ineffective with almost immediate bleeding through white emulsion. Most screwfix products are good quality but in this case no nonsense means no good"
"I used this on an old dry water stain and it does not work at all!! I wish I read the prievious reveiws as I dont seem to be the only one saying this. Its a shame as lots of the 'no nonsense' products are good."
"it does not work on old water stains, i did 4 coats and it still bled through, being a damp expert i know the stain was dry enough for most stain blocks, i shall stick to zinzarr in future its a couple of quid more but when your in centeral london on a sunday mornign you need it to work firsty time.."