Only a comment about PVA adhesives. There are many different kinds, but for this application I would recommend one of those that is “water washable”. Elmers makes some that is about $10 per quart on Amazon. I’m sure there are others.
The non-washable PVA adhesives will cross-link as they cure, making them more difficult to remove from the surface they were applied to. Some will cross-link enough that they become very water-resistant (for example Titebond 2). The washable PVA adhesives also tend to be cheaper than the ones intended for use as wood glue.
I did a comparison (if you can call it that) with the same setting using LBT100 spray… I’ve had good luck with this spray, even though it’s rather expensive. The color tells me I’m burning it too hot and there are areas that are ‘closed’ up. Such as the eyes at the bottom.
Zinc oxide fumes (not vapor, since it is a very fine solid particulate) are a concern, but with reasonable ventilation in the work area should not be a problem for laser engraving. You actually have to inhale quite a bit for it to cause significant health effects. Of course, if you have other health issues, you might want to be more cautious.
For most people exposed to ZnO fumes, the worst effect is what feels like the onset of a case of the flu. One common “treatment” or prophylactic measure is to drink a glass or two of milk after exposure to the fumes. The ZnO is not absorbed through the lungs, but is expelled with other lung mucus and ends up in the digestive tract, and is absorbed there. Milk interacts with the ZnO and reduces the absorption in your gut.
The only death from ZnO fumes I have ever read of was rather a stupid thing. A guy with seriously compromised lungs decided to remove the galvanizing from a bunch of pipe in his shop. He decided to build a fire in his wood stove, then put the pipe in through the open wood stove door. His wood stove wasn’t drawing very well anyway, and with the door open, most of the ZnO fumes ended up in the shop, but he still elected to stay there with it for some reason. Reports were that dense white smoke was pouring out of the shop for a couple of hours, and when someone finally entered the building the guy was quite dead.
Welders have to deal with galvanizing from time to time, and a decent respirator will protect you. If only welding a little galvanized material, a lot of welders don’t bother with the respirator. For laser engraving, even a big job involving Zn or ZnO would cause fume issues that are easily mitigated by reasonable ventilation practices.
Hi Jack. Hope you had a good weekend. I was experimenting ceramic engraving using Titanium Dioxide Ti02 with PVA Glue and water mixture as suggested by Ron in one of his forum reply. Unfortunately the result is not Dark and sharp after engraving. See photos attached. How many layers do you generally spray over the tiles.? I did only 2 layers. I also noticed when using the normal hand spray container it is not fine. I started to add a little more water to dilute further but spray extra layers. If necessary I’ll be happy to buy a battery operated spray gun with higher power. Thank you. John
Why do you guys insist on using a spray. I simply use a 1" soft brush and the cost is much cheaper, no mess to clean up, and the results are perfect. I’m now using the latest modified formula. For best results with a brush on method measure out 100 ml of PVA glue and I now add 3 tablespoons of water plus two drops of liquid hand soap. Mix thoroughly. Now add one full tablespoon of titanium dioxide to a flour sift. Slowly mix sifted powered to your PVA as you stir. Make sure you mix well. I now strain this mixture through the flour sift into another vessel. Paint on clean tile as you would paint anything with gloss paint. I dry with hairdryer and laser at 1000 mm/m 80% power. 40 watt diode laser.
@RonClarke is the person really working with this…
I get dark blacks, but I use a lot more TiO2 than he does and I coat it with a sponge brush… What I’m using now has the consistency of mayonnaise… The last few I’ve messed with I’m using the fiber on them…
Although an air brush is low cost and works, I think better than a brush, it’s a pain to clean up. Sometimes the TiO2 plugged it up.
I’ve been using the foam brush… I’ll post a couple pictures…
Glad to hear it John and very keen to see your results. I also tried the foam brush but could not get a smooth finish. I now use a ladies makeup brush with very soft hairs. Works a treat. I paint left to right, up and down and finish with a corner to corner stroke.
Here is one I did recently.
Thank you Jack. You are right using Airbrush need speed to clean up and the container cannot put too much of the Ti02 mixture. so it involves much time. My Airbrush is already I’ll follow your method and add slightly more Ti02 powder, and using Ron’s method by using fine ladies make up brush. Will try again over the weekend.
Thank you Ron. Wow your recent engraving looks really nice. I will follow your suggestions closely and I’m sure it’s just how many test more before I get there. With highly experience users like you and Jack I will not give up. The last mix I put 3 full teaspoons of Ti02. The next test I’ll add perhaps one more teaspoon plus slightly more water so it will not be so thick and try. I’m also looking at buy a portable spray which much stronger instead of using Airbrush.
Thank you again. John
I probably mentioned somewhere above, but I put a little bit of red food coloring in the mix. Helps you see what you’re coating if you’re doing this on white tile. It really shows up when it dries… You can see places you’ve missed…
Thank you Jack. I did put a bit. No wonder I cannot see if there are any patches that’s not well covered. Will add more water colour paint next round. Thank you.
Wow really nice. I just hope I can do it and will not be giving up so easily. I’m using Neje Diode Laser with A40640 which is 40W and the Laser module is around 15W.
Hi Ron ! Thank you for your reply. Well I’ve bought fine makeup brush to follow your current method. You have been most helpful and I look forward to sent you photos of what I have done as soon as I complete engraving. One thing I will do is to add some water colour so I can see if the Ti02 is covered evenly before engraving. All the best . John
Yes 3 tablespoons of water. This I have found helps the mix to level out after painting and remove most of the brush marks. Good Luck and I’m looking forward to seeing your results.
Little late to the game, a HUGE shout out to @RonClarke for coming up with this. Here is my first photo sample on tile. Havent rinsed it yet so may lose some details/crispness. Literally my first run after a few material tests. LM3 using the Ron Method, 6x6 Lowe’s tile, that photo is about 60mm wide 254 DPI, processed on PhotoShop Sauce Script
That is looking very good. I’m sure you will not lose any detail. Once dry I’m sure you will be pleased with the result. Do let us see the washed finished tile.
