..... on 1.74 lens polishing

**mauroventura** · 03-30-2009, 10:20 AM

Hello.
It is a period of discussions with the lab-guys who build lenses for my coating lab :angry:.
Rencently we found problem on 1.74 concave sux lenses after hardcoating.
Looking defects with a stereo-microscope i see small cuts (less than 4/10 mm) on the hardcoat surface circular-arranged near the border of the lens (in a crown of 20 mm of thickness) .
Problems of lens polishing ??:bbg:

What can you think about it ??

**chip anderson** · 03-30-2009, 01:08 PM

Hard coat isn't usually polished after application. Doubt if it can be done. Same with AR or any other coating.

Chip

**mauroventura** · 03-30-2009, 03:43 PM

Originally Posted by chip anderson

Hard coat isn't usually polished after application. Doubt if it can be done. Same with AR or any other coating.

Chip

Hy Chip,
I mean :
problems of lens polishing before hardcoating phase.
My suspect is that something is wrong in the polishing equipment during the polishing phase ( in the RX lab).
Probably the temperature of liquid polisher is too high

Mauro

**mike.elmes** · 03-30-2009, 05:07 PM

Fine and polish marks should not be visible on surfaced lenses...certainly a viable reason to return the lenses to your lab.

**mauroventura** · 03-31-2009, 02:06 AM

Originally Posted by mike.elmes

Fine and polish marks should not be visible on surfaced lenses...certainly a viable reason to return the lenses to your lab.

...This is the strange thing!
If i look the lens surface uncoated (just polished) with a spot light i can see nothing but the normal signs of the polishing . This defects( small cuts ) start to show them after hardcoat!

Mauro

**chip anderson** · 03-31-2009, 06:27 AM

Evah heared o' crystalization?

**mauroventura** · 03-31-2009, 08:24 AM

Originally Posted by chip anderson

Evah heared o' crystalization?

'Evah Heared' ?
I don't think it's a crystalization because if i look it with my stereoscopic microscope i can appreciate a small depth cut on cc surface.

**chip anderson** · 03-31-2009, 09:25 AM

See what you see with a polariscope or polarised filter on your microscope. Let us hear.

Also remember that coatings are essentially paint and paint doesn's always dry evenly and sometimes finds spots or lines that it does not adheare to as well. Not to mention that any surface the more highly polishied it becomes, the more flaws show up. Every time I think I have a prosthetic eye "smoothed" enough to polish, I find several places that were not as smooth as I thought and have to give them special attention.

Don't know what you can do with lens surfaces to "give them special attention" but it is a possiblilty that this is the source of your "flaws."

For what it's worth I spent more time than you have been in the optical business as a surface polisher in both glass and contact lenses. I know surface flaws.

Chip

**mauroventura** · 04-02-2009, 06:43 AM

Hi Chip.
My RX lab solved the problem on 1.74 lenses.
It seems ,the problem was born due to a broken filter in the polishing liquid recirculation system of LOH TORO XL polishing machine.
This is the " rx-lab official version"

.
Anyway now all it's ok !
Thank you again for your suggestions.

Mauro Ventura