Why damp tissues?

[Steve Crawford]

So it may be a basic question, but why does Trotec recommend wrapping a wet piece of tissue around a glass or bottle when engraving? Here is a beer glass which came out Ok with no wet tissue.

However there is some degradation to the letter B in Bert and the Wi of Wishes, would these have been better if damp tissue had been used? This was engraved at power 45% and speed 25% 500ppi on A Speedy 300 which has a tube measured at 89.3watts.

284819

Any advice appreciated. I want to get this right and not have the degradation in the image.

Cheers, Steve

[Scott Shepherd]

Steve, it's my understanding that the wet newspaper (not a tissue), helps flatten the beam out a little and make it not as harsh when it fractures the glass. Lasering glass is nothing more than micro fracturing glass. You're creating tiny fractures in the glass that are so close they look uniform. The beam is hot and precise and putting the wet paper on there softens that process a little, I think and makes it not quite as harsh on the glass. There have been many threads about whether it works or not. Some people swear by it, some people say they did extensive testing and they cannot find any difference at all, so your milage may vary.

It's worth a try.

[Dan Hintz]

Steve,

Skip the wet tissue and lower your power... you look too hot, hence the chipping. This also assumes you're running at around 70% black... if you're not, keep your power the same and drop the black level first.

[Dave Sheldrake]

Damp paper blocks the scattered IR round the edge of the beam, in effect it *can* make the spot size appear smaller and reduce scatter as well as helping prevent the spread of heat. Tends to work better with RF sources as they *usually* have a better beam profile.

cheers

Dave

[Dan Hintz]

Go to your room, Dave, until I find time to discuss your transgressions in more detail ;)

(I'll PM you my thoughts later this evening).

[Dave Sheldrake]

Go to your room, Dave, until I find time to discuss your transgressions in more detail ;)

(I'll PM you my thoughts later this evening).

:P

cheers

Dave

[Ross Moshinsky]

30w laser. 600dpi - 100pwr. 30 speed. Full black. Soaking wet newspaper packing material.

It leaves a nice frosted etch with no real depth. This is the only way I've consistently gotten "good" results out of the laser on glass and crystal. I personally found low DPI made it look much worse. Letters weren't crisp and I found fracturing and chipping to be much worse.

If I were you, I'd increase the speed to 70% and use wet newspaper and see how things go.

[Steve Crawford]

Thanks for the advice all, I'll try out so,e of the suggestions. Dan, you mention 70% black... Are you referring to the colour of the design I set in Corel, from the Trotec pallet? Currently I've either been using full black or blue for any engravings. Does grey therefore make a difference when it gets to Job Control?

[Scott Shepherd]

Thanks for the advice all, I'll try out so,e of the suggestions. Dan, you mention 70% black... Are you referring to the colour of the design I set in Corel, from the Trotec pallet? Currently I've either been using full black or blue for any engravings. Does grey therefore make a difference when it gets to Job Control?

He's talking about in CorelDraw, instead of picking black from the Trotec Palette, use the standard color palette and pick 80% black or 90% black and send it over. It's been known to help a great deal.

[Steve Crawford]

He's talking about in CorelDraw, instead of picking black from the Trotec Palette, use the standard color palette and pick 80% black or 90% black and send it over. It's been known to help a great deal.

Oh I see. Is there something wrong with the grey colours in the Trotec pallet then, meaning the standard is better for this?

[Scott Shepherd]

Oh I see. Is there something wrong with the grey colours in the Trotec pallet then, meaning the standard is better for this?

Yes, completely different. Well, the gray is like 40% black or something. You want 80-90% black. It just spaces the dots out a little bit and gives you more of a minute pattern in the engraving that can help make things look more uniform.

[Mike Audleman]

Yes, completely different. Well, the gray is like 40% black or something. You want 80-90% black. It just spaces the dots out a little bit and gives you more of a minute pattern in the engraving that can help make things look more uniform.

Hate to necro a 5mo old thread but I got a question here...

What format are you exporting from CD? I have been exporting to DXF and then importing that into RDCAM (came with the laser). That then sends it to the laser.

I am not sure where setting a color in CD would affect my laser. Please help me understand! I so want to get glass working. I shattered some dollar store glasses and marginally etched one. The etch is very grainy and chippy in consistency and, frankly, looks like -a-cola. I used masking tape, didn;t know about the wet paper until now. Gonna try that tonight (maybe tomorrow).

I would appreciate it if you could guide this blind dog through the process from CD to laser so I can at least get things in the ballpark.