Ultraoptics Mini II chipping backside of Transitions, and ideas?

**snowmonster** · 11-02-2009, 02:35 PM

So our Mini II has been doing great until recently when we've noticed extremely small chips in the back/minus side of Transitions lenses. It only happens with those lenses, no problems with Polycarb or even regular CR39. FWIW, the chips are usually somewhere near the central 1 centimeter of the lens.

The wash cycle is using deionized water and we're cleaning the back of all lenses with a mild detergent and isopropyl alcohol prior to coating.

We thought maybe it's blasting the lens too hard and that the Transitions material might just be a little more brittle? If that's the case, is there some way to actually reduce the pressure of wash cycle from the pump?

Thanks in advance!

**snowmonster** · 11-02-2009, 03:20 PM

Here's an image taken with the slit lamp camera. It's not an easy thing to photograph, but the light is shining from the left to the right on the back surface of the lens.

It seems to do it more during the dry cycle.

**DragonLensmanWV** · 11-02-2009, 03:44 PM

I haven't had that problem, the problem I get the most is air bubbles in the coating, even after I bleed the filter. It can take a dozen tries on some lenses to get a good coat.

**snowmonster** · 11-02-2009, 04:21 PM

So I ran that same lens through about 20 times and got 3 large (like the one in the picture) chips and then a bunch of subtle "dents" in the lens. All of them are within 6 mm of each other. Our Transitions lenses are Sola products.

I did the same test with an uncoated Vision-Ease CR39 FT28 clear lens and absolutely no dents, chips or anything. Both lenses were surfaces the same way. 2:15 minutes of low speed fining time with a 1-step pad, 4 minutes of polishing on low speed. Cleaned the same way with each lens.

Could it be a manufacturing issue?

**Didier** · 11-02-2009, 04:22 PM

Did you do tape test to be sure the adhesion is good ?? Most of the time, when you can see these chips, the adhesion is very bad and you need to change your UV lamp or your lacqer.

**snowmonster** · 11-02-2009, 04:56 PM

Originally Posted by Didier

Did you do tape test to be sure the adhesion is good ?? Most of the time, when you can see these chips, the adhesion is very bad and you need to change your UV lamp or your lacqer.

I'm not even coating it. I'm just testing to see where the chips/dents are coming from. So you run the wash/dry cycle and the chips/dents are already there.

**DragonLensmanWV** · 11-02-2009, 05:11 PM

I would polish for longer than that, try 6 minutes.

But, the substrate for Transitions is different than CR-39 or any mid-index. Are these Transitions 1.50? You might try posting this over in the Transitions Forum and maybe Jim will have an idea.
All powers? More of a problem with flatter back curves or steeper curves? Just thought it might be dropping too low and hitting the orifices. What kind of air pressure you running? I use IPA for cleaning bath, not DI water.

**snowmonster** · 11-02-2009, 08:30 PM

Good point, I'll post over there, I forgot there was a Transitions forum. I'm just glad to hear the substrate is actually different. The lenses always "felt" different to me after coming out of a hot cure oven.

I'll run a test lens tomorrow and polish for 6 minutes - could that really do something? Again, we've always polished for 4 minutes for CR39 and Transitions 1.50 and we haven't changed our pin pressures, fining or polishing pads at all.

Yep - Transitions 1.50. It seems to happen on pretty much any curve. I can tell you the lens is not physically hitting anything. My lab guy suspected that at first so I lifted the suction cup a bit. We're running at 100 psi to the machine (which makes me wonder see below), we use to use IPA up until about 6 months ago and then switched to deionized water to reduce flammability risk and cost.

So the Haskell pump in the coater shoots high pressure water or IPA at the lens. Is the dry cycle simply powered by the shop air or is it also with the pressurized air from the Haskell pump?

**gemstone** · 11-02-2009, 08:48 PM

Originally Posted by snowmonster

Good point, I'll post over there, I forgot there was a Transitions forum. I'm just glad to hear the substrate is actually different. The lenses always "felt" different to me after coming out of a hot cure oven.

I'll run a test lens tomorrow and polish for 6 minutes - could that really do something? Again, we've always polished for 4 minutes for CR39 and Transitions 1.50 and we haven't changed our pin pressures, fining or polishing pads at all.

Yep - Transitions 1.50. It seems to happen on pretty much any curve. I can tell you the lens is not physically hitting anything. My lab guy suspected that at first so I lifted the suction cup a bit. We're running at 100 psi to the machine (which makes me wonder see below), we use to use IPA up until about 6 months ago and then switched to deionized water to reduce flammability risk and cost.

So the Haskell pump in the coater shoots high pressure water or IPA at the lens. Is the dry cycle simply powered by the shop air or is it also with the pressurized air from the Haskell pump?

Could be some undetected fractures from the generator. Compare those settings. It does not make sense that the coater causes this.

**FVCCHRIS** · 11-03-2009, 01:01 AM

That's weird! OK, I got it, don't backside coat transitions.

Seems like it would be easy to track down the culprit. Only transitions? Have you tried changing out the rubber suction cups?

**snowmonster** · 11-03-2009, 05:56 AM

Originally Posted by FVCCHRIS

That's weird! OK, I got it, don't backside coat transitions.

Seems like it would be easy to track down the culprit. Only transitions? Have you tried changing out the rubber suction cups?

Haven't tried that but not sure how it would help. The chips/dents are on the side to be coated (the back side).

**DragonLensmanWV** · 11-03-2009, 07:03 AM

Originally Posted by snowmonster

Good point, I'll post over there, I forgot there was a Transitions forum. I'm just glad to hear the substrate is actually different. The lenses always "felt" different to me after coming out of a hot cure oven.

I'll run a test lens tomorrow and polish for 6 minutes - could that really do something? Again, we've always polished for 4 minutes for CR39 and Transitions 1.50 and we haven't changed our pin pressures, fining or polishing pads at all.

Yep - Transitions 1.50. It seems to happen on pretty much any curve. I can tell you the lens is not physically hitting anything. My lab guy suspected that at first so I lifted the suction cup a bit. We're running at 100 psi to the machine (which makes me wonder see below), we use to use IPA up until about 6 months ago and then switched to deionized water to reduce flammability risk and cost.

So the Haskell pump in the coater shoots high pressure water or IPA at the lens. Is the dry cycle simply powered by the shop air or is it also with the pressurized air from the Haskell pump?

I think the dry cycle is just shop air. 100 PSI isn't too high, but I have mine running at 85.
The extra polishing can get rid of microfractures, maybe that's allowing the air to penetrate the lens.

**snowmonster** · 11-03-2009, 07:14 AM

I'll buy a regulator today and try it, can't hurt.

Thanks again.

**snowmonster** · 11-03-2009, 11:38 AM

Okay, so I tossed a regulator with filter on the coater and cranked it down to 80 psi.

Ran a 1.50 Transitions FT28 of the same curves that was generated, fined and polished the same exact way through the wash/dry cycle 10 times with absolutely no dents/chips/defects as viewed with a slit lamp microscope and naked eye.

Still strange since we had no trouble until a few months ago and nothing really changed, but at least it worked so that's cool.