Best Masking Type and Technique for Semi-Curved Surfaces?

[Doug Fisher]

I have been etching pint glasses that have curved sections in both the horizontal and vertical directions. This curving makes it difficult to effectively cover the glass with masking/transfer/application tape. It results in bubbles, gaps, folds and creases. When the etching laser passes of each of these, it usually produces a faint but noticeable irregularity in the etching. Applying longer masking pieces horizontally to wrap around the glass seems the worst. I tried doing multiple thinner vertical strips of masking but matching the seams is really difficult and I still get some gaps, folds and creases.

I have researched the archives here quite a bit yet didn't find much information in regard to techniques that could minimize these issues. Some posts said you have to tweak your settings more although I have not been able to find settings that can reproduce the sharpness and nice white frosting that masking provides. I would like to avoid the liquid masking products if possible.

Thanks in advance for tips and advice.

[Mike Null]

Try doing the job without tape in 3 passes. Reduce your power and dpi settings and change your focus with each pass. Some people advocate the use of dish detergent as a mask.

[John Lifer]

I've been working with wine and alcohol bottles. No masking. straight plain glass. Increase your gap interval to 0.04 (equivalent to 625dpi) In my experience it makes it look much better than what I'd tried before. Might try several passes, that definately could help too.

[Doug Fisher]

Thanks for the feedback. I will try dialing the power back to almost nothing and then do multiple passes. The settings were already at 600 dpi for resolution. I now kind of wish I hadn't tried masking. Most people probably would have been fine with the unmasked results. Unfortunately, now that I have seen the slight but noticeable improvement (especially the crisp small text), my perfectionist nature is getting in the way of being efficient for business (not selling any of these yet but trying to learn just in case an opportunity arises!).

[Mike Null]

Doug

I have an ongoing job where I use 333 as my resolution and make 3 passes It is a small logo but must be perfect, hence the 3 passes. I shoot for a frosted look rather than the "deep" engraving.

It is a customer's logo otherwise I would share it.

[Doug Fisher]

Thanks, Mike.

[Kev Williams]

I'm with Mike on the resolution, another case where (for me) less is more- I've found high res settings can cause more 'pop-offs' of fractured glass- my thinking is the close spacing results in the laser running over the same place too many times and causes heat stress, and the glass fractures easier (or so it seems to me)... Mike is using lower res AND lower power, both of which lowers heat stress on the glass. This works great! --- for him ... I say that because ALL machines are different, and of my three C02 machines, only my LS900 engraves glass decent. The other two I've spent hours with cheap mirror tiles and setting changes galore and still can't come close to results that I like...

[Glen Monaghan]

In addition to using 300-ish resolution, try 70-80% black for the engraving rather than 100% black. I find that helps with creating more of a frosted effect that has less tendency to spawn "large" fractures (that leave relatively smooth spots) as compared to the micro-fractures (that create a frosted effect).

[Mike Null]

Glen

You're exactly right. In my old age I forgot to mention that.