I have to respectfully differ with Stoneshop on this one. As a rule, quartzites are too dense to absorb anything, much less a sealer. Applying a sealer to this stone would be a waste of time and product, since you will totally wipe up anything you apply to it.
If you argue that applying sealer could do no harm then, you are not correct either. If you apply sealer and do not totally clean up all the residue, the remaining sealer will dry on top of the stone, causing it to be difficult to keep clean. It will be streaky and dull looking where the sealer residue was not totally removed.
The ONLY purpose of a sealer is to prevent staining through absorption. If nothing will absorb to begin with, you have NO problem - therefor no need to apply any sealer.
To see if you stone needs sealer, just test it with some water dripped on a sample or an inconspicuous area. Leave it a while and blot it off. If the stone got darker where the water lay, you would need to seal. If not, don't bother!
Many of the issues we see with stones that are difficult to keep clean, are a result of sealer that had been applied in error and not cleaned off properly. The second most common reason for "maintenance issues" with granites and quartzites we get, is wrong cleaning products. Cleaners that contain oils (corn oil and canola oil are big culprits) or waxes (carnuba wax is a no-no!) build up residue on the polished surface, causing streakiness and dull spots.
My philosophy regarding stone is: the less you do to it, the happier it is. The much stated "fact" that all granites need sealer, is probably THE biggest myth bar the stories about the existence of Bigfoot or Chtulhu :)
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