Slate Engraving test runs
I have a bunch of slate floor tiles at home, and since engraving actually works quite well on slate I figured I need to do a proper test run.
What makes the floor tyles a bit less desirable to engrave is the lack of contrast. Since these are grey slate I think and not a black slate the final image can almost disappear if you are not viewing it from the right angle.
With this example in the photos I actually coated the engraving in black enamel and for the most part was happy with the results. I did need to increase my power since quite a few bits of enamel was not burnt through. I removed those bits just with a hand grinder.
At first I thought I could run the laser again over the same space but the registration was off by 3mm and when I noticed it had already removed some of the detail in the roses on the bottom.
Before I engrave I also do a clear coat which is really the least effort to at least darken the surface slightly but it still lends itself to low contrast on the image. Someone said I should try oil which I can try on the clean slate, and the background might be a shade darker, and ideally I would want to see if the oil penetrates which might reduce contrast if the lower layers are also darkened.
A raw base with no coating on the bottom, before I decide I want to do an enamel test. I lost quite a bit of detail due to different pixel requirements but the test showed that the enamel would be great for contrast. Obviously. However it did not prepare me for the added thickness requiring higher power to burn at.
Overall I am happy with the tests, mistakes were made but at least I know which ones. I do now want to try and split and break these floor tiles since they are way easier to get than roof or coaster slate tiles.
You know that is a damned good Idea. I've been thinking of doing some screen printing as I have a dark basement to work in (emulsion and screens rack up costs quick though) but a print made from a slate engraving would work like a charm. Either a monoprint or by using several pieces of slate you could do a multicolored print.
What power laser cutter are you using?
I only have a 10W Diode laser so materials can be a bit limited, but I can still do glass also and mark good stainless steel, also anodized aluminium plates since you basically cut the coating, then I saw some people spray paint multilayers on canvas and engrave on that. It is time consuming though, that is a 30cm square image and took about 3 hours after some tweaks with initial tests at 4+ hours. I am actually looking at screenprinting as a nice option but that will come when I am willing to drop the money , for now I decided I should test straight up block printing , the engraver I think can cut me stencils on wood but if that is sucky I could try stencils on laser rubber and just roll fabric paint or whatever surface I am working with paint over I think. The screen printing I think would be a great addition to the bleached and reverse tie-dye shirt types,and with rubber I guess also you can do pad printing, but the rubber is pricey over time vs I feel a screen.
Thanks for the info. I asked because there is lots of scrap slate around here. Mines/quarries are only a 30 minute bike ride away.
With silk screening my only concerns are the emulsion costs. 4 hours is a long time for the laser but far quicker than doing it by hand. :D What's it like on copper or PCB circuit boards (mountains of scrap around you can sand down)
It would depend on the image you are engraving also, I tried for high detail on a completely "grayscale" image but I think I could have doubled my speed and power output and would not have lost too much detail once I figured out what made my edges seem blurry. Slate is quite forgiving also I guess since you can just sand it down although with these floor ones the lighter slate is not too far from the darker surface, each material will have its quirks.
Metals you might need to get a marking spray, stainless steel is the only one that has some kind of natural reaction to the diode laser, all the others you need marking spray and even then it might be best with a co2 laser , I think it is possible on diode but will take a bit of testing. All else fails if you can coat the metal first then remove coating with engraving then that is always viable I guess. Only metal I have tested was a pair of nail clippers for stainless steel and anodized aluminium dog tags. No clue about PCB , might be similar to acrylic so maybe you can cut it and even engrave with Diode (budget) likely definitely co2 and fibre.
Thanks for that. Good that I have you to teach what is th better buy and what to use. :D