Unlike wood that gets darker the longer/higher power, slate is all or nothing.
With some images you can make the dithering work. But that image looks like too little contrast and too much detail.
Mineral oil can help improve the contrast.
Slate is a natural material and how they react vary. Some turn out white, some grayish, some yellow or gold. It’s a crapshoot. Usually a set of coasters from the same supplier all react the same.
You can easily remove any markings on slate with some wet sandpaper and a little elbow grease.
You’d probably be better off using the norton white tile method.
There is definitely a lot of material variation with slate. I have a large piece of slate here that I’m experimenting with and the ‘burned’ sections are coming out DARKER than the rest of the slate, which is dissapointing as there is very little contrast.
I’d love to know the material properties of the type of slate that gives a nice bright white burn, I’m sure it’s a specific geology but until then I’ll just have to keep trying until I find a supply that works.
Yeah, there are numerous materials. Till now I have used plastic, wooden, and paper coasters. I haven’t used a slate coaster till now but I would like to experience it. However, I have a small doubt, If the slate is used as a coaster how it can prevent the spelled liquid? I thought the coaster material must be paper-like so that it can soak the liquid stain and keep the table safe. Sorry if I am wrong.
@alexpor4567 :
Coasters have 2 modes (in my mind). Absorbing condensation is perhaps ideal[Footnote], but just isolating the cold/damp from the (presumably wood) finished surface to be protected is the other. I don’t think coasters prevent “spills” - they don’t usually have a tray-like lip of any kind. (I guess a third reason might be if you have fancy cut crystal type whiskey glasses, that sort of thing, that can scratch the wood on their own…)
They sell all sorts of machined stone coasters too that aren’t very absorptive but trap condensation drips in the surface grooving.
The slate coasters I buy have little rubber or foam feet so the stone provides a thermal mass but also is spaced from the surface to be protected. Slate top face is a little porous on its own. If you finish/seal it, yes that does reduce the porosity for any actual absorption of condensation ‘into’ the stone’s porosity. (I use a cutting board sealer product - which is basicallly beeswax or carnuba wax with some walnut oil, walnut oil being one that will actually solidify at room temp and NOT go rancid and have a smell – and the combination is food safe – on mine).
@Dinkelborg :
Getting the right contrast takes a couple tries and is different for every file and dithering type. I tried some dot matrix type too and in my case ended up looking perfect for one after lasing - but then had actually too LITTLE contrast from the original slate surface after I added a sealer. That was a “wish I could take it back” moment. So far I’ve had more luck with halftoning lines and vectors (both outline and fill). If you look back up this thread at my picture with the 4 different coasters, the “Surf Arrakis” one is way too dark after the finish, which is a bummer. It looked great in that shot. Tatooine and Ishimura coasters were vector (fill), and the Alien ship with the barely visible “send more colonists” due to reflection was a greyscale done with line halftoning. The Surf Arrakis is the only one that was a dot matrix dither attempt.
[Footnote]: We had some of those white ‘stone’ coasters with engraved grooves. They do absorb a little perhaps, not just trap the water in the grooves, but their downside is if you don’t wash them after repeated wettings, that leftover moisture eventually starts to mildew and the grooves get gross. Took a toothbrush and some bleach water to restore. Which also semi-ruined their backing, a solid flat layer of cork… Icky!