Getting frustrated, seeking advice

Community Laser Talk
1

I’m working on trying to get TiO2 to work on glassware (with rotary), on a 100w co2. I’ve read and watched all kinds of stuff, and and experimented a bunch. The issue is that I get chipping, which I’m trying to avoid, not just because I want it to look nicer, but when the image/words are black, the chipping removes it.

Things I have tried:
Speed: 300 and 400mm/s
Power: 12.5-35%
Jarvis and newsprint dither.
DPI: 150-500 (dot width correction 0.03)
Black %: 100-50

I’ve narrowed down a few things.

  1. speed doesn’t seem to make a difference, other than being able to go faster, bearing in mind power vs speed.
  2. Jarvis looks better than newsprint.
  3. 500 DPI looks better than lower. 500 is where I do pretty much everything after watching a very detailed video posted here.
  4. power seems to do best around 20ish. More makes it darker, but almost more…melty.

I have a little hair sprayer that I mix rubbing alcohol and TiO2 powder in. I don’t really have a ratio, I just mix till it’s a consistent white. I spray on a coat, hit it with the heat gun for a few seconds, and repeat for 3 coats. I tried brushing it on, which didn’t work at all. I tried using the air sprayer, which was ok, but seemed so thin that it didn’t even blacken. So I’m unsure if maybe my application could be better.

Clean up is just hot water, and a scrubby sponge. Then I lightly hit it with a brass wire brush.

I’m just trying to get black frost, without buying the $80/can laser marking paint lol.

Pics included:

Considering all of my other examples I’ve done tonight seem to vary in chipping, even when changing nothing, I can only assume I could be applying things better, or im totally missing something.

2

Far from an expert - but I Been doing some experiments over time.
I found TiO2 works great on - some - tile but glass results are very very varied.
Temperature, glass thickness, laser power, dot size all add such a high degree of results change i was never able to get a result that would be replicable enough to “create a product”.

Have you tried CerMark though? Its quite expensive but i think the results quality might be worth experimenting.

Final thought too on your laser - 100W might be TOO wide beam too much power. But i would let the CO2 experts in the mind hive to give their 2 cents.

3

I haven’t tried any of the laser specific products yet. Most are too expensive to even sample. I see those guys have a tiny bottle though, so I may give that a try some time, though I don’t know if that would justify the cost (adding in material cost vs what I’d sell a glass for).

4

This is the issue - however a can of Cermark goes a long way.
My proposition was more - research as it might be wroth it
If you have a output of 6 in 10 glasses come out good enough to “sell” for example, the added cost and stress of throwing away materials might add up fast.

5

Lets take a few and talk about what’s happening… although you probably know, just to be on the same page.

Glass has virtually no thermal expandability and the heat transfer is very low to the surround glass. When you heat a small area, it tends to absorb the heat and expand a slight amount, then breaks from the surrounding glass. These breaks aren’t necessarily or always what you’d call a clean break.

A friend is a glass artisan. He advised me to use steel wool on the engraving after it’s done and not gently. If a shard of this gets into a customers (or your) finger, it’s next to impossible for a doctor to find and remove. I have some steel wool that I’ve used on many pieces of glass work that have never scratched the glass.

How TiO2 and LBT100 (and Cermark) actually work … the coating is heated by the spot, the coating becomes hot enough to form a molecular bond with the glass. I have used LBT100 for a number of years… I get mine fro Amazon, but it’s about $80 for 12oz spray bottle.

The coating can be thick, where you loose detail and require more power, most of these recommend a very thin coating. Higher resolution, less power. Coating thickness is a real bear and you will have to experiment with different types of applicators to see what works best for you. If it’s a spray can, it’s pretty simple but care is required as it’s easy to overcoat these and have poor results.

Many of these products work well on porcelain tile which seems to be a different type of glass. I have quit using them on some types of glassware as the setting are very critical. If you get it hot enough to bond, it may heat the glass enough to break, which is what you’re experiencing. Simply too much heat.

I’m sure you can do this with TiO2, but I didn’t have the patience to detail the settings and it varies by glass type. This link has a lot of ways to mix TiO2.

There is molylube, don’t get taken by this, it produces sulfur dioxide that then combines with water and oxygen to produce sulfuric acid. This is why the laser coating are so expensive… they are safe for you and your machine.

You might try tracing the graphic, then using a fill instead of an image with stucki.

You need to figure out your spot size, as the proper interval is related to spot size.

Good luck

:smile_cat:

1 Like
6

Is my assumption correct that you want a black letter rather than a white frosted letter?

@jkwilborn said it best here.
When the fragment pops out, it takes part of the black spot you just made.

I had some success when a customer preferred a black tint on some shot glasses. I used black acrylic spray, and fortunately they found the not-so-black acceptable.

If you get this figured out, please post the results.

7

Hey jack! I always appreciate your responses.

I tried lower powers, but still got a little piece here or there that chipped. I believe the chipping is only happening after cleaning. I use a brass wire brush to lightly go over the glass while cleaning it. I know that some of this is the pure randomness of glass. That is, I understand that we aren’t technically engraving it, it’s surface marking, and micro fractures are those markings. As such, there’s no way to know what direction those fractures take. Comparing to normal engraving however, changing none of the settings, I can only assume the TiO2 is to blame. Whether due to user error, or just simply because it’s a foreign substance introduced into those fractures.

I haven’t seen anyone using dry moly. But I appreciate the words of caution.

I’ve tried using the text in Lightburn as fill, creating text in Photoshop to make it an image, changing the image black %, and outlining the letters with hard black (to sharpen it).

I’ll check out the link about application methods you provided.

There was a YouTube video posted here that I found that was about an hour long I believe, that went over all the technical side of spot size, finding your DPI, etc. After following that, 500dpi is my best number.

Maybe drinking glasses just aren’t the best medium for TiO2? Lol. I did a piece on flat glass that turned out neat, so idk.

8

Maybe when it appears to you, but it’s likely the laser heat causing the cracks… Easy to check out, use your cleaning method on a new glass and see if it breaks little pieces… I think you’ll find the glass is fine.

Unless it’s really a really small ball-peen hammer… :scream_cat:

What makes this so delicate is there is a certain temperature it needs to reach to fuse the material to the glass. A slight variation may cause it to bond better and/or create a stress crack.

I just don’t do this with regular glass mugs/cups using a coating… I’ve never gotten satisfactory results with this method on glass… likely not enough patients on my part to really dial it in…

I do a number of things with glass. Anything handled by people I scrub hard with a steel wool pad… So I doubt you’re actually causing this to crack.

:smile_cat: