Cloudy residue after engraving cast acrylic

[MC Design]

I made some keyrings recently that had letters engraved on the face of the cast acrylic, however during engraving a cloudy liquid appeared over most of the keyring (presume its the material liquifying after being hit by the laser), it doesnt seem to wash off, anyone know of any household products that will remove it?

[tweakie]

From my experience Acrylic vaporizes when attacked by the laser so any surface residue will be acrylic and will not "wash off". You may be able to remove it with an abrasive such as "Brasso" or "T-Cut" etc but the best solution would be to mask the surface with paper "transfer tape" prior to engraving. An alternative approach could be tangential "air assist" to prevent the residue settling on the surface of the work during engraving.

Hope this helps,

Tweakie.

[Spooky]

helps? youre not kidding Tweaks, that's just given me an idea.........

back in a bit

[Pedro_Hernandez]

I've had this problem before, I played around with the speed and power and succesfully elimanted the cloudy white residue without the need of a application film or clean up.

The only playing I did with the Air assist was the force it came out of the nozzle, make sure your optics are clean and focus is spot on and if at all possible do a multiple pass etch at lower power untill you reach your desired depth, weirdly playing with DPI(scan gap) settings can help reduce cloudy residue as well.

Regards

Peter

[PhillyDee]

Wish I could adjust the power on the fly! Some of us were too poor to afford anything but the basic model (or the one that fits through my front door, and up the stairs )

I wipe my plastic parts with acetone and microfibre cloth to get rid of this. Apply acetone to cloth, wipe plastic. Wear nitrile gloves!
Of course, it is not recommended, apparently it can cause stress fractures, though I have yet to find any.

[MC Design]

cheers for the help guys, i was in a bit of a rush so used the closest thing at hand, automotive paint compound haha, worked a treat

[Meta-Concepts]

Bought some 3mm acrylic from Techsoft and whilst some of what I ordered is branded Perspex, much is unbranded and gives a terrible amount of cloudy residue.

I tried a wipe over with Acetone and when I held the job up to the light to check, I was able to watch stress fractures slowly spread across the whole thing like crazy paving!

Ran it again and tried IPA instead of Acetone but still ended up with some stress fractures around the edges. Third time, I used 4mm sprayed with Silicone lubricant and then washed and finished with brass polish.

With 5mm Perspex, I have no great smut problem in comparison.

Terry

[Mike]

Extruded acrylic easily cracks with cleaning agents IPA etc, AFAIK cast acrylics don’t crack...
You can use cleaning agents on extruded, just don’t soak it in the stuff, I normally dab it on the cloth and then rub the cloth on another surface until it’s just barely damp.

You need to specify what you want at time of ordering. Your supplier may question why you need cast vs acrylic but at least they are paying attention.

Generally cast engraves leaving a white surface and acrylic engraves leaving a clear surface, so they have different uses. i.e. if you want to reverse engrave and do a coloured paint fill you need to use extruded.