How to Seal a Vertical Sandstone Wall

What You'll Need
Damp Cloth
Paint tray

If you want to have a sandstone wall in your garden, then you may be anxious to weatherproof it. Weatherproofing or sealing will help the wall to last for longer, and you can also give the wall an attractive coat that will enhance its appearance. When you want to seal the sandstone wall, you will have to find a few good days in order to allow the wall to dry out after it has been sealed. If you do experience any bad weather after the seal has been applied, you might need to re-do it.

Step 1 - Clean the Sandstone Wall

The first step is to make sure that your sandstone wall is completely clean. This is necessary because the sealant will act rather like a varnish, so any dirt or debris underneath the seal will be highlighted. When this happens, it is too late to do anything about it, so the best solution is to clean off the sandstone before you begin. Give the wall a thorough clean, taking care to remove any loose bits of stone.

Step 2 - Prepare the Wall

You should then sand down the wall. This will not only smooth it out, but you will also be able to create a texture on the wall which will allow the sealant to hold onto the sandstone. You should use a sander for any large difficult areas, particularly if stone has broken away and left sharp edges, and then a piece of sandpaper should be taken over the edges to completely smooth them down. When this has been done, look at the wall, and make a note of any significant gaps. These will need to be filled in with caulk. Apply the caulk, and then leave overnight to dry before applying the sealant.

Step 3 - Prepare the Sealant

Find a sealant which is suitable for use on sandstone. A multi-coat sealant might be the best option, as it will adhere to most materials, including sandstone. You could also find a brand particularly suited to the stone, although this may require several coats to fully secure the wall. When you have the sealant, Take a paint try or large plastic food try, and pour the sealant out into it.

Step 4 - Add the Sealant

Wipe down the sandstone wall with a damp cloth to remove any debris, and then start applying the sealant with a paintbrush. Start from the top, and work downwards, not adding too much sealant to the brush, as this can cause it to drip down the wall. Steady, slow strokes are best, and you should be able to cover the wall using the sealant. Remember to push the brush into any curves, dips or corners, as these will need extra coverage. Ensure that the sandstone wall is completely covered, and then leave to dry.