How do I waterproof seal exterior slate?

[Vinod]

I have outdoor slate tiles on my balcony on the 2nd floor, I have used Crommelin products so far but they don't seem to last, needs to be recoated annually and the oil-based sealant stinks 

[EricL]

Hello @Vinod

Welcome to the Bunnings Workshop community. It's great to have you join us, and thank you for sharing your question about how to seal exterior slate. 

What sealer from the Crommelin range are you currently using? Some sealers like the Crommelin 4L Natural DiamondCoat Slate And Stone Sealer are water repellent and will not change the appearance or look of the slate. It does not form a film so will not increase the chance of slipping. 

However, the Crommelin 4L Satin DiamondCoat Slate And Stone Sealer will enhance the natural colours and pigments of the slate. It has a low sheen coating and provides surface protection from stains. 

Here are the links to the TDS of the Crommelin products:

• Slate & Stone Sealer - Natural
• Salte & Stone Sealer - Satin

If you need further assistance, please let us know.

Eric

[Vinod]

Thanks Eric for your prompt response,  I have used Crommelin for three years now, with two coats.  I seem to have to reapply them annually and being an oil-based paint it stinks. And this is a balcony in a private house- low traffic

Is there a more resilient product out there?

[MitchellMc]

Hi @Vinod,

I'd like to hear more about the balcony and what method you're using to know the tiles need re-coating. Crommelin slate sealers should be lasting for at least five to eight years. If you are applying them annually, you're undoubtedly putting multiple coats on top of each other, and this will cause the product to fail. It needs to breathe and can't do this with constant coating.

Is there a leak in this balcony by chance, and are you using it as an indicator that the tiles need re-coating?

Mitchell