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Honed quartzite gritty - Calacatta Gold

7 years ago
last modified: 7 years ago

I chimed in on the Is Granite supposed to be smooth? thread last week, and thought I might as well start a new thread in case folks have similar issues with quartzite (or, in case the issues are different altogether). The CG delivered to the shop was polished, and we had it honed in the shop. Counters/Island top were installed last month, and the crew sealed with two coats of GranQuartz sealer (Impregnator 413S, I believe) -- several days between coats. We noticed a grittiness on the sealed surface. Not knowing if perhaps the crew didn't clean the surface thoroughly enough (and perhaps locked in some sand/grit), they stripped and re-sealed. Still grit.

I spoke to GQ technical rep, who recommended stripping with Lithofin (Wax-Off, from what I can recall), then applying the GQ 353p Impregnator for porous surfaces. This was done by the crew. Days later, same results. As we ran a razor blade across the surface, a white powdery substance can be seen on the metal:

The owner came out Tuesday and re-stripped the counters -- he wanted to make sure all the correct steps were followed. Instructions were to follow-up with clear water rinses; so when he left, I continued to apply water, slightly scrub surface with a stiff nylon brush, and let dry. Same result: grit.

FFwd to today: Fabricator is a member of Marble Institutes of America, and he gave me the contact info for his technical consultant at MIA. What the MIA rep told me:

  • It's possible my set of slabs were taken very close to the surface of the quarry, which could explain grittiness coming from the stone itself. I didn't quite get his exact explanation, but perhaps surface veins/structure isn't geologically jammed/compressed as tightly as the stuff far below? (My words, not his.) Regardless, he didn't think this was a likely explanation.
  • More likely that the white stuff is the original sealer that was applied onto stone which wasn't allowed to dry properly. He explained that a lot of water is used in the honing process (true); and a very dense stone such as quartzite takes a long, long time to dry out before sealer should be applied. He surmised that the time between in-shop honing and sealant application (~ 2-3 weeks) wasn't nearly enough.

Question of the day: how long does freshly honed quartzite take to thoroughly dry before sealant can be applied?

Answer: 3-4 months (<<< not a typo).

I'm sure it's a reasonable assumption that the vast majority of honed quartzite installers out there are NOT waiting 3-4 months before sealing the stone. This would require the homeowner to potentially have a 'down' kitchen for that amount of time before the counters could be sealed (and worry about staining in between). Tech said that, actually, most stones are so dense that they don't even need to be sealed. I told him that in all the reading I'd done, while that is true of many of the darker granites (AB, Black Pearl, etc.), CG quartzite is known to be porous and should be sealed.

Bottom line is that if we don't wait for the quartzite to completely dry out (again, he emphasized months), we'll apply an initial coat or two of sealer, and end up having to re-strip and seal again.

Would be very interested to hear anyone else's experiences, specifically with honed CG (or Macaubus White, which is the same stone, but vein cut), sealant process, etc.

Also odd is that through these various stages of stripping and sealing and re-stripping and stripping again, now I'm wondering if it's the resin (originally applied in Brazil, presumably) that's getting dissolved by the strippers, and that's what's powdering up. Any pros out there wish to chime in?

After the Tuesday application and multiple water rinses, I detected a lot of 'pores'/holes that had the same powder-white substance caked into the hole. When I poked at these with the corner of the razor, the powder came loose.

And just this morning, I noticed a lot of pitting that I don't recall was there before (though may very well have been, and I didn't notice):

I do realize that I'm dealing with Mother Nature and natural is what it is, at this point. The honed sample I was given certainly came from a different part of the stone that didn't have this complexity in it. I went with the honed because the leathered sample had too much pitting (resembling orange peel), and I didn't want that much texture in a food prep area.

Of course, it's now late Friday afternoon and I won't be able to pick up the conversation with my installer until next Monday.

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