Help!! Lens keeps getting stained!!!???

[Zsolt Paul]

My old lens developed a blotchy gray transparent stain on it. I zoomed in and turned to black level up in PS to make it a little easier to see. In reality its a bit more faint. It was actually almost impossible to see at first. I tried cleaning it with my "fomula MC" lens cleaner, alcohol, acetone.... even desperate enough to try vinegar, but NOTHING had any affect whatsoever on the blotches. So I ordered a new lens. Put in the new lens and after a DAY (!!!!) of running the laser, the new lens now has the same exact blotch on it. Needless to say I was fuming. Once again, nothing is able to remove it. It kills 50% of my power and cannot get smooth 3D carving. Apropos, I was cutting maple and cherry and doing some 3D carving. Air assist nice and stong, no fumes or smoke getting back up to the lens. I suspect it is moisture. It is very humid here these days and even with my moisture tube on the air assist, I noticed some "spits" on the lens. I am guessing that these might be some mineral deposits that are staining the lens?????? Can anyone suggest how to clean them? I can't keep buying new lenses. Thank you!

[Craig Matheny]

I will go with moisture do you have a drier on your compressor line?

[Joe Pelonio]

Deposits on the lens are very common for wood cutting, but maybe the moisture makes it worse and stick more. A good lens cleaner should take it off, though. One trick to decrease moisture in the air is to have the compressor at a lower level than the laser, and use a long hose. Coil it up many times near the compressor, then add the water filter and then up to the laser on a short but steep run.

[Craig Matheny]

Also 100% Grain alcohol works great as a lens cleaner but I think I read somewhere or was told not to use acetone. The main thing with the hose is distance from the compressor to the drier or separator the air needs time to create the moisture prior to the drier

[Rodne Gold]

Route the air assist to bypass the Lens box and to be directed at the point of lasering. Our lenses were getting DIRTIER when they were pressurised

[Zsolt Paul]

I can't believe i forgot to add the picture in my first post. Here it is now.

Great idea Rodney! Although my immediate concern is if the air is not coming OUT OF the nozzle, rather sort of from the side of it, will that allow more debris to make it up to the lens?? I think it would definitely eliminate moisture drops on the lens, but will smoke/debris/w/e make it up the nozzle easier?

I do have a long hose from compressor (which is lower than laser) to moisture seperator.

I stil can't believe that it can't be cleaned off after a day of usage!202354
http://www.sawmillcreek.org/images/misc/pencil.png

[Dan Hintz]

Zsolt,

Send me your old lens and I'll take a look at it... pics are going to make it difficult to determine what's on it.

[Frank Corker]

It'll be the sap from the wood which has heated and attached itself to the lens coating. Be careful too much cleaning will result in the lens coating being removed. I would also recommend a soak in a quality lens cleaner.

[Mike Null]

I'm inclined to agree with Frank. Try running without air assist. I don't like air assist at all on raster jobs. When I'm running a high volume of wood I will clean my lens every hour or two.

[Zsolt Paul]

Dan, thanks for the offer. I appreciate you willing to take the time to look at it, but unfortunately, its the only lens I got for cutting. What I did is rotate it within the lens holder (I dont mean upside down) and thankfully, the beam is currently missing the spots and is working fine. I am on the lookout to make sure I don't mess up this section too. It seems there is simply no way to clean off this kind of stain. It seemed to have absorbed into the lens coating itself. I have tried every suggested method (short of grain alcohol), but I doubt that's stronger than acetone.

[Craig Matheny]

Acetone can damage the coating on the lens try the grain alcohol that is epilogs cleaner they use at the factory and suggest in the manual. I had a spot in the middle of my lens could not clean it Epilog replaced it under warranty I ran out of lens cleaner they said grain alcohol so I got ever-clear (Same thing) and it works great then tried it on the other lens I could not clean and little rubbing with a q-tip soaked in this stuff cleaned it right off now I have two lenses. Try the grain alcohol and if it does not due the job you can drink the balance so it is a win win.. Good Luck

[Mike Null]

Actually reagent grade acetone is highly recommended as an optics cleaner and as I recall ULS packs that with their machines.

http://www.iiviinfrared.com/optics_handling_cleaning

[Craig Matheny]

I just go off my epilog manual and it states that Acetone should not be used as a regular cleaner so that is telling me if it is used to much or incorrectly that it will have adverse effects on the lens, that is all I got to go by. But at this point and time the only thing not tried has been the grain alcohol so we just have to wait and see if that works.

[Zsolt Paul]

Laser Research also recommends acetone with a swab.

[Mike Mackenzie]

You should not use too much acetone when cleaning the lens not because it will damage the optic but it releases the glues that hold the optics in there mounts.

Paul,

I would inspect your air system it sounds like there is a leak in the line somewhere and when using the cones it acts like a vacuum instead of a pressurized cone

[Martin Reynolds]

The concern with acetone is that it can attack the adhesives used to bond optical parts. Some lenses (not IR laser lenses) are two lenses bonded together, and acetone would be bad there. Other optical lenses are glass-plastic hybrids, and will take immediate damage from acetone. Also, laser mirrors are probbaly epoxied to their mounts, so there is some risk with acetone here. Wiping witha drop of acetone will be fine. An acetone soak could cause problems. The adhesive would degrade only slowly, and it isn't in the optical path, so acetone isn't the risk that it might be with other lenses.

[Craig Matheny]

"Actually reagent grade acetone is highly recommended as an optics cleaner and as I recall ULS packs that with their machines."

I looked at this and then decided to see if I can buy this type of reagent grade Acetone at a local hardware store and I could not they only have a standard Acetone. " The contaminant-free purity of ACS Reagent Grade Acetone is desired as a special-purpose solvent, particularly in cleaning laser optics and other delicate lenses and mirrors. science company com/Acetone-ACS-Reagent-Grade
So I do see for some companies you can use Acetone but I guess we need the reagent grade Acetone i guess you get it from your local chemistry store or your laser manufacture. I personally will stick with the Everclear so when I do have a bad lens I can drink my sorrows away with the rest of the bottle:D

I hope you can get that lens clean.

[Mike Null]

Craig

I'm pretty sure Everclear is fast acting so it won't take much to drink your sorrows away. I believe it's 200 proof.

[Craig Matheny]

In California 151 proof is all we can get:(