No Nonsense Stain Sealer White 400ml (31649)

Hello Tovi, The coverage is 1.75-2 m²/Ltr but you might be better off using a paint on sealer if you have a large badly stained area. Thank you for using Q&A

Hello Frubes, Painting a surface after the Stain Sealer has been used may prove problematic due to it's water resistant properties. Thank you for using Screwfix Q&A. A.K.C.

Hello Davidh5271, This product is suitable for use on painted surfaces. If the stain is due to water ensure that the source is dry before application and for patches where mould has grown it will need to be treated with a biocide before application. Thank you for using Q&A

Hello, Yes, this will seal old dried water stains no problem. However, RE the tar stain, the oils from the tar have the potential to block the stain from sticking to the surface very well. If the tar stain is on the surface you would need to wipe as much of the tar off. A white spirit or sugar soap may help to break down the oils in the tar. You can then gently sand the area to remove more of the tar and create a suitable key for the paint/stain sealer. If the tar has bled through from somewhere else then 1st it is advisable to make sure the leak which caused the initial leaching/bleed to be fixed. You can then wipe with white spirit/sugar soap and gently sand to create a key. As the tar contains oils it may be better to use a primer, sealer and stain killer. This is better suited for sticking to more difficult surfaces. Thanks for using Q&A

Hello, The issue with this is that the stain sealer may struggle to stick/adhere to the parts of the walls that have wax residue left on it. It may be a good idea to gently sand or clean the areas (with a sugar soap or similar cleaner) effected by the wax first, to help the stain sealer stick. As long as the stain sealer can stick, then it should be fine to cover the remaining stain. Thanks for using Q&A.