Sandstone sealer

Sandstone sealers for sills, cladding, garden walls and facades - invisible ones that leave the stone in its own shade, and wet-look ones that permanently deepen its colour. They limit the water uptake that destroys this stone from within.

Element or wall
HP-1 was tested for sills, cladding, garden walls and details. VP-1 has the same composition but was developed for sandstone walls and facades.
Colour
HP-1, VP-1, EH-20 and EH-21 leave the colour of the stone unchanged. ProtectGuard WL Mat and WL deepen it permanently - matt on rough stone, semi-gloss on smooth.
Oil and stains
On steps, a sill or a wall by the barbecue, choose a water- and oil-repellent product: EH-20 or EH-21 also limit the ingress of oils.
Consumption
Sandstone drinks a lot, and unevenly. Seal a trial square metre and measure what it takes, and with EH-20 expect to be near the lower end of its 4-12 m²/l coverage.

7 products

Guides

Before you choose: how to pick the right product, prepare the surface and what to expect once it is on.

The absorbency of sandstone is also its weakness. Water gets in deep, carrying salts that crystallise as it evaporates and burst the stone from within. On a facade there is also the cycle of soaking and freezing - the main way this stone is destroyed in the Polish climate. We show how sandstone compares with granite and travertine in the Natural stone section.

Four routes for sandstone

  • HP-1 and VP-1 - water-based, single-component siloxane sealers, colourless once dry. They penetrate deeper than 5 mm, leave the way open for water vapour and are rainproof after 5-6 hours. HP-1 for elements, VP-1 for walls.
  • EH-20 - water-based, silane and colourless, it limits the ingress of water and oils. It takes a day to dry, and you work with it between +10 and +30 °C.
  • EH-21 - a water-based fluoropolymer dispersion free of petroleum solvents. It repels water and oil, limits salt efflorescence and suits sandstone on both vertical and horizontal surfaces.
  • ProtectGuard WL Mat - a wet-stone look without the shine. You apply two coats 15-30 minutes apart, and a litre covers 10 m².

Pale sandstone turns noticeably warmer under a wet-look sealer. We compare the two finishes in the guide invisible sealer or wet look.

Order of work

  1. Wash the stone. Green growth and atmospheric dirt come off with C-11E: dampen the surface with clean water, apply the cleaner and rinse thoroughly after 2-3 minutes. Start with a test somewhere inconspicuous.
  2. Wait until the sandstone is dry not just on the surface but in the pores. The full list of conditions is in the guide to preparing the substrate before sealing.
  3. Apply the sealer until the stone is fully saturated - with a soft roller, a brush or a sprayer.
  4. Protect the freshly sealed surface from rain and direct sun.

The most common mistake

Judging the colour straight away. A freshly applied sealer looks like a wet surface whatever finish it is meant to give. Judge it once fully dry, and with ProtectGuard WL Mat after 5-7 days, because only then does the final look settle.

Questions before you choose

Will a sealer change the colour of sandstone?

An invisible one will not: HP-1 and VP-1 leave the colour and texture of the stone as they are. On a very absorbent, matt surface, though, an invisible sealer can slightly deepen the shade simply by filling the pores. If you want a distinct change, choose ProtectGuard WL Mat or WL - that effect is permanent.

HP-1 or VP-1?

The composition is the same - what differs is the use each was tested for. For elements and cladding choose HP-1, for walls and facades VP-1.

How much sealer will sandstone drink?

More than granite; how much depends on the stone. HP-1 and VP-1 are applied to saturation, so seal one square metre, measure what it took and multiply by the area with a margin. EH-20 covers 4-12 m²/l, and on absorbent sandstone you will be near the lower end.

When can sealed sandstone take rain?

HP-1 and VP-1 are rainproof after 5-6 hours. Until then, protect the stone from rain and direct sunlight.

Why seal a sandstone facade?

To limit the cycle of soaking and freezing that destroys this stone. VP-1 limits the ingress of rainwater and the compounds dissolved in it, while the pores of the stone stay open, so the wall still releases moisture.