No Water Seal should not be used before plastering or in any interior applications. Water Seal will not seal a porous surface or act as a bonding agent to increase the adhesion of plaster.

No. The hydrophobic properties of Water Seal will negatively affect the adhesion of any paint applied over it.

No. Water Seal can only be used on bare and uncoated brick, stone or concrete.

If applied correctly, Water Seal will last up to 4 years. This is dependent on conditions such as orientation of the wall and local climate.

Water Seal contains additives to reduce beading during application because of its water based formulation. Allow the surface to weather, and after a few days beading will become apparent.

Applying Water Seal will not damage wood, but the level of waterproofing protection will vary depending on the type of wood being treated. For best results, we would recommend a dedicated preserver to protect exterior timber from rot.

Yes you can paint or apply wallpaper over the wall however, you will need to leave the coating to dry for 8 hours before overpainting.

Patio & Block Paving Seal Natural finish will not change the colour of the stone. Wet Look and Satin finishes are clear but the colour of the stone will darken after application, as the seal enhances the natural grain and colouring. We recommend testing a small inconspicuous area first with your chosen finish before application.


All of our Roof Seal products can be used on pitched roofs, such as sheds and outbuildings. They can be used on slates, tiles, felt and corrugated metal surfaces.

No, there is a danger that the chippings will puncture the dried membrane leading to failure.


Our Floor Levelling Compound can be used to level depths from 3 mm to 5 mm. Latex Levelling Compound can be used to level depths from 3mm to 10mm. Deep Fill Floor Levelling Compound should be used for depths above 10mm


Yes. The latex content  in Flexible Rapid Set Floor & Wall Tile Adhesive gives enhanced strength, making it ideal for use over underfloor heating. Existing underfloor heating should be turned off and cool before applying the adhesive. If you are installing new underfloor heating, our Latex Floor Levelling Compound should be used to embed the elements, and leave the surface level and ready for tiling.

Yes. The water resistant formulation is suitable for both interior and exterior use.

Concrete and Mortar Repair

Yes. The surface should be primed when any additional coats overlap onto weathered or porous areas.

This product is supplied as a powder. Take the required quantity of powder and mix with water (see pack for mix ratios) This product should be mixed and applied within 20 minutes as mixing or applying once the cement is setting may impact the strength of the cement.


Yes. Usage levels are based on a combination with OPC and may need to be adjusted. As with any mix, a small test batch should be made to check colour intensity.

No. Liquid Cement Colour is not designed to be applied as a top coat. It should be used in the mix and bound into the hardened concrete.

Chloride Free Frostproofer & Rapid Hardener can be used in the mix from -4⁰C and above. However, the temperature must be above +4⁰C to lay the concrete

No the surface will not accept a paint coating after application.

Concrete Dustproofer & Rapid Hardener dries clear, although it can give the surface a slightly darker appearance.

Yes SBR Waterproof Bonding Agent will resist freeze thaw cycles in the set mortar, but  it will not accelerate curing times.

No, this product needs to be applied in dry conditions before it will become water resistant.

Yes. Usage rates are based on a combination with OPC. When using other types of cement, their properties, including hardening rate, should be taken into account when considering addition rates.

Yes, although the render or plaster should be applied onto the top coat of SBR whilst the SBR is still tacky.

No. Integral Waterproofer is designed to improve water resistance in external masonry mortar and render. It is not suitable for use in damp proof courses.


Yes. Thompson’s Acid Brick Cleaner can be used to remove stains from brick, stone and tarmac. However, a small test area should be cleaned first to check for any surface damage or discolouration.  Contact with calcareous stones (for example travertine and marble) should be avoided.

No. Acid Brick Cleaner is formulated to remove cement and mortar splashes as well as grease and grime from stone, brick and concrete.

Yes. Acid Brick Cleaner is suitable for internal and external use. When working internally, care should be taken to ensure thorough rinsing after use. Metal work (including taps etc.) should be protected, as contact with the cleaner will cause corrosion.

No, the application of Acid Brick Cleaner on limestone or sandstone is not recommended as there is a risk that the acid in the cleaner will react with the stone and cause staining. We would recommend Advanced Patio & Block Paving Cleaner for this application.

Yes, however, to prevent the risk of compatibility issues and to ensure that the paint is applied to a sound surface, the surface should be washed and cleaned prior to application of the paint.

Mastic Putty and Oils

Yes. If the putty under the skin is still a workable paste then it is still usable and the skin may be discarded.

Our Putty is available in Natural and Brown, but can be overpainted if required.

Yes, but it must be used with Dow Corning 796 when installing sealed units to conform with the requirements of the following standard: BS: 8000: Part 7: 1990, Glass and Glazing Federation Manual Section 4.2 and NHBC Standard 6.7c July 1995.