laser onto glass

[Malj]

Hi iv'e been lasering onto glass vases and getting some different results. The image is generally good but requires some cleaning to remove the residue that is left behind, once the residue is removed the image underneath is good. Does anyone have any suggestions how to achieve clean lines that don't require work after the laser has done its job. I have tried high power low speed and different variations between high and low still have to clean the excess off.
Some suggest wetting the item to be worked on, putting damp paper on or washing up liquid!!

Thanks

Mal

6840
lasers cut 5.3

[SimonMallas]

Hi Mal,
Never had a problem with residue, but I always use wet paper with the air assist off when engraving glass. Thanks for the info Dave, an interesting read and I do know that people do struggle with engraving onto glass. The only really advice I can give is don't over egg the pudding! Too much heat will over fracture the surface and wet paper does help localise the heat.
Lasering vs sandblasting?? Well it just depends how much experience you have in either! I do deal with engravers and have been put on the spot several times! The most resent was at trophex, on a busy stand, when the owner of swatkins thrust an large expensive looking glass trophy at me ask for something engraving on it! I was going to brush him as the stand was busy, but when he said gravograph had made a real mess of one! Red rag bull....... I'll post the pictures of the results, which ended up on swatkins stand : ) All down to practise and experiance.
Sorry Mal not much help! keep playing sorry mean researching......

[Natalie]

Hey there,
I've recently been etching a lot of electro plated glass for some experiments here at work. (and the odd wine bottles)
We find that laying two layers of newspaper and wetting them until dripping works and keeps any residue off the glass.

I find that wine bottles always come out well, I guess due to the contents dissipating the heat.

[Jerry]

you mean you don't empty them first
Jerry

[Spooky]

All down to practise and experiance.

And what type of glass

best wishes

Dave

[SimonMallas]

Hi,
Thanks Dave : ) Yes all glass isn't the same, as with most materials. It's always wise to run a few tests.

[StarLoc Adhesives]

I do some glass coasters of things like bulgarian monuments and mountain pictures for a company in Bulgaria doing tourist items, we mist them with water first as i was told to by the supplier o the glass , it seems to work

Not all glass is the same though.....

I remember the day chris delivered my machine, i suddenly wondered if it would mark glass bottles.....we tried a brown glass bottle we use to pack our polyweld plastic weld glue, the bottle had never been filled with anything ( so nothing flammable was in it ),chris wasnt sure as we didnt know the type of glass , as the laser it it a fraction of a second after chris tried to mark it the bottle it cracked into bits

[Spooky]

It's stress in the glass that causes the problem

Glass in itself is a very strong material, the problem is the flaws and impurities. If glass could be manufactured in an anhydrous airless vacuum it would have 40 times the strength of steel and be considered a structural material. The problem is crystal defects and surface cooling.
As soon as heat or stress or pressure is introduced into the surface (for plate rather than float glass) you end up with problems

Float is better for engraving as it has far less stresses introduced during manufacture but plate and toughened can cause all sorts of problems (hehehe I've seen a 20 foot by 12 foot 1/4 sheet go pooooofff) the problem with float is you can have legal issues if fitted within 800mm of the floor (it has to be toughened) as it tends to break into shards...

I did some time at Salisbury Glass as a lead draughtsman and some of the stuff they do with the material is amazing but does illustrate just how many different types of glass there is

Dropped glass tadpoles used to be the party trick, a tear drop shaped piece of drop that you could beat with a 4kg sledge hammer at the head end and nothing happened.Flick the tail end with your finger and the entire tadpole explodes

I'm not a big fan of glass engraving with a laser, marking yes but for pictures there are just too many variables.

A quick tip for bottle / vase engravers?

Take a piece of cotton string, dip in methylated spirit and tie round the bottle about half way up.

Set fire to the string and leave it to burn out (takes about 8 to 10 seconds)

Drop bottle in bucket of water and hey presto , nice straight cut off without needing to buy a bottle chopper

best wishes

Dave

[SimonMallas]

Hi All,
Here are some pics of glass engraving done for the torphex show.

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Hi Dave, ya toughened glass is full of stress, you can physically see it with a good pair of polorized sun glasses. You just wouldnt believe a liquid could be so brittle! and you use ultrasonic to cut it up!!! (before being toughened)sound more exciting than the actual process of running a little metal wheel over the surface, which shooting fractures down through the glass allowing air in! Its similar to what were doing with a laser. The aim is to remove and damage the surface, but not so it causes too much damage (fine line). Keeping the beam and heat as localized as possible will stop the fracturing speading keeping the edges sharpe. Using wet paper is king in my opinion.
Cheers Simon

[SimonMallas]

Hi,
Heres the pictures of the Swatkins trophy done at Trophex.

Cheers Simon