How to seal a slate floor?

[shirley123]

I have lived in my home for 30 yrs and have a black slate floor throughout most of the house. I have sealed it several times with gloss sealer. I have battled with small amounts of white on slate. Stripping and sealing but it reappears.   I also have used a brush but seem to leave brush marks no matter how I try.  Any suggestions.  Nearly driving me mad.  Its time to do some of it again.   Thank you 

[JacobZ]

Hi @shirley123,

Welcome to the Bunnings Workshop community and thank you for your question on how to seal a slate floor.

Is it possible for you to upload some photos of the affected area so our helpful members can better assess what the issue is and offer advice on its potential cause and how to fix it?

It's possible that the "white" you are finding appears on the slate over time is efflorescence. Efflorescence occurs when natural salts and minerals within the material are carried to the surface by water penetrating through the slate. If you are sealing the top of the tiles but are still finding the efflorescence reappears, you may have moisture finding its way underneath the slate which might require some investigation by a professional as it could mean there is a bigger issue lying beneath.

This is a possible cause, but it is difficult to determine the issue without seeing it. Once you've uploaded some photos, we will be better able to assess the issue and offer further advice.

Let me know if you need some assistance uploading photos, I am more than happy to help.

Jacob