I was gifted two small pieces of granite (smaller than a coaster, little under 3/4 inch thick). It is not glass smooth, but flat. I tried to wash it and it has this powdery white haze, that darkens when it is wet, then returns when it drys. I tried googling but all I got was polishing. Wht is a better term to use or how can I fix it? I want to try engraving and probably filling with color.
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Sorry, don’t understand what you are asking to “fix”. All natural stone will appear darker when wet vs. dry. Is it a dark or light colored stone? And are you sure it’s not a marble vs. granite?
Do you want to make the surface smoother before you try to etch it in the GF? Make it thinner than 3/4" inch (assuming you mean 3/4" and not 34"). For making it smoother/polished, or thinner, LOTS of sanding, but its not really difficult to sand/polish it, just takes time and patience and lots of grits and finishing with 1000 or more and polishing compounds.
Marble is usually softer than granite, so responds to cutting/sanding/polishing faster…
You can always remove the crumb tray and use blocks to get the surface to a workable height for the GF. I’ve etched honed marble, others have etched rougher rock surfaces, so you should be able to try it as-is.
If you want to add color, you can mask the surface and color before removing the masking after etching, but it it’s rough surface, there will be some bleed. But you could always do a deeper etch and sand/polish after adding the color to remove the stuff on the top and then expose the stone again and your color-filled in areas.
Worst case, if you don’t like what result you got, you can then go through the sanding & polishing operation to remove the depth that’s been etched and try again…
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well… it’s supposed to look like it does on the right when dry. that’s the normal colouration of the granite. We have countertops that have a very similar granite (probably the same).
It would have been polished already (the reflections at the bottom near the break suggest that it is).
If you want it to always look like the wet sample, you can probably apply some mineral oil on it which wont evaporate.
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As a point of information, marble, even when variously colored is all Calcium carbonate with tiny differences in minor chemicals causing the colors. This is very different from Granite that every different color is a crystal of different materials. It is hard to say exactly what each color is. If you are grinding and polishing it this does not matter, but putting a laser to it is not as risk free as marble or slate.
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This kind of appearance is why you will often see cabochons of turquoise and similar stones treated with epoxy (such as Epoxy 330) to retain the deeper color of a wet stone. That’s what I would recommend doing here.
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