Hi there,

I've pasted an excerpt from a previous thread below, also included the link. Hope this works for you!

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They used an industrial silicone-based sealant from GranQuartz, called 413S. I'm not certain that it is available to individuals (as opposed to fabricators), but it might not hurt to ask your fabricator about it. I've pasted in a link to the product on the GranQuartz website.

Here is a link that might be useful: Sealing quartzite

I was having difficutly with sealing my countertops with Bulletproof from Dupont, it would allow water to darken the slabs. The counters were stripped of Bulletproof and then 511 Porous Plus was applied. They function flawlessly now. If you are having difficulty with your top consider this product.

We also have 511 and it's been perfect but you do have to remove your current sealer before you use a different brand.

Wondering if the Aspen White still holds up with the 511 Porous? I just installed Aspen White in a bathroom and am having the same problem. The water is absorbed leaving dark spots that eventually dry and disappear.