Yellow CR39 Lenses

**lguess** · 04-15-2002, 11:20 PM

I've come across a bunch of CR39 lenses, both coated and uncoated that have yellowed. In years past I've tried to "save" lenses that have yellowed with no success. Before I throw these lenses in the dumpster, use them for target shooting or donate them to a school for practice and take a tax deduction do any of my fellow Optiboarders have suggestions to get the yellow out?

Thanks in advance!

Larry

**Steve Machol** · 04-15-2002, 11:21 PM

Try bleaching them in the sun for 1-2 days.

**LENNY** · 04-17-2002, 11:05 PM

Use them!
If the second lens is not yellow add some yellow to it and tell the patient that you put uv on them at no charge.
They will be happy

**Judy Canty** · 04-18-2002, 09:34 AM

How about taking the tax write-off and donating them to your local Opticianry training program?

**fly** · 04-22-2002, 10:08 PM

I have seen yellowed lenses that were dipped in the blue dye pot for about a second look pretty clear. Just and idea let me know

**harry a saake** · 04-23-2002, 08:44 PM

:D Dip them in some brown tint so they become amber. old folks love them.

**bwheeler** · 05-15-2002, 10:17 AM

You are probably the owner of some very old lens inventory. Most quality lens manufacterers have been adding uv inhibitors in their stock lenses for many years that prevent this yellowing. Even so, I rotate my stock by replacing new foci to the back of each set and pull stock from the front of the set so that I am sure to use the oldest lenses first. You may be able to use this inventory for sunglass rx's too. IE. Second pair half price lens deal. That is if there is no way to donate it to a suitable organization.

**Farhan Hassan** · 10-30-2012, 09:36 AM

hithe best way i have tried so many time, just give them a sing dip of blue BPI tint. then leave them in open air for 1 hour . INSHALLAH you will find positive result.

**Jacqui** · 10-30-2012, 11:26 AM

I use a few seconds to a couple minutes in lavender tint.

**Tallboy** · 10-30-2012, 12:28 PM

they will pry my ancient high cyl yellow CR-39 lenses from my cold dead hands. So valuable for calibration.

**Jacqui** · 10-30-2012, 12:37 PM

I just noticed, this thread is 10 years old

**Chris Ryser** · 11-01-2012, 03:19 AM

Originally Posted by Jacqui

I just noticed, this thread is 10 years old

..............and the lenses have become nearly brown but still have no wrinkles.

**Farhan Hassan** · 11-29-2012, 03:15 AM

BUT HE SOLUTIONS ARE CONTINUE

LET THE NEW FRIENDS KNOW THE TECHNIQUES

**idispense** · 12-07-2012, 11:26 PM

Most CR 39 lenses exhibit a certain amount of yellowness referred to as YI or yellowness index, as well warehouse yellowing is noted, as is UV and thermal ageing. Bluing agents will help to mask this . Higher temperature AR and scratch coating processes will aggravate the yellowness.

The best source of information on this subject would be PPG Industries.