Hydrophobic Top Coats

[Falstaff]

At present the top coat of our AR stack is a fairly standard hydrophobic layer. We are aware that there are now super-hydrophobic coatings available with impressive contact angles.

There has been some reluctance from our customers for us to supply coatings which are so slippy that they might be difficult to edge with their existing technology. We just wondered if many people across the world are now using super-hydrophobic coatings, and whether there are problems getting leap pads to stick to them etc.

Any information gratefully received.

[Chris Ryser]

At present the top coat of our AR stack is a fairly standard hydrophobic layer. We are aware that there are now super-hydrophobic coatings available with impressive contact angles.

..................... the world are now using super-hydrophobic coatings, and whether there are problems getting leap pads to stick to them etc.

Hydrophobic coatings have been around since 1987 and the first Super Hydrophobic was introduced in 1990 with added anti-fog and anti static features. So it is not so new after all.

IThere are now good leap pads available and the edgimg is not such a tough deal anymore. There are also some coatings availabe that can be applied after edging.

[Falstaff]

Thank you. That is very useful information for me to pass on to the powers that be.

[chip anderson]

But is it or is it not the case that the more layers of coatings one has them the possibility of separating from it's adjoining coats?

Chip

[IC-UC]

At present the top coat of our AR stack is a fairly standard hydrophobic layer. We are aware that there are now super-hydrophobic coatings available with impressive contact angles.

There has been some reluctance from our customers for us to supply coatings which are so slippy that they might be difficult to edge with their existing technology. We just wondered if many people across the world are now using super-hydrophobic coatings, and whether there are problems getting leap pads to stick to them etc.

Any information gratefully received.

I think that most would be now using the Super-Hydrophobic. I certainly know that most manufacturers we work with only do the best top coating available.
There are products out there that will stop the slipping, but it will always be a bit of an issue. I would think the use of the super coating would outweigh issues with slipping.

[Murray O'Brien]

I think I can offer some advice on this subject. Pretty much everything on offer here in Australia is now super hydrophobic and I struggled for a long time keeping them on axis during edging. Most of the manufacturers supply those clear stickers that go under the leap pad and on the back surface of the lens as well. They are really fiddly and time consuming as I'm sure you know. Then I found these super sticky blocking pads made in Italy called "secure edge plus" They should be available through your parts suppliers that stock centrostyle gear. So with those pads alone, and using "soft" function on my Nidek edger, any non Trivex lens is no problem. Do still have problems with high minus and high prism trivex though. Only way I've found to solve the problem is to do the job in two steps. Cut big first then re-block and cut to size. Very time consuming stuff so always try to convince my clients not to order trivex high minus or high prism with super hyrophobic.
So, yes you will need to give your customers some coaching on edging if you do change.
By the way, we use a lot of Hoya Phoenix (trivex) VP and SFT coating. VERY slippery but vitrually never come back peeling

[Falstaff]

Many thanks. It would seem that super-hydrophobic lenses are now widely being used, and that it is possible to successfully edge them.

[Alon ST]

Hi There,

There are currently Super hydrophobic lenses that are manufactured with a thin microfilm layer. This completely resolves the need for stickers for edging! and all the issues involved (working with a sticker applied wrong can still ruin the lens)

to locate manufacturers of these lenses simply google Microfilm Ultrahydrophobic

Cheers,
Alon Eliya

[Jacqui]

Your web address doesn't work.

[The Maltese Falcon]

Hoya's Super High Vision is most impressive.

[Murray O'Brien]

Alon ST.
Microfilm is good but what if you have a problem and have to reblock the lens? The microfilm comes off, so you still need the clear sticky pads under the leap pad or a pad that is super sticky as a backup system.
The Maltese Falcon.
Super High Vision? I think that is marketed here as "VP coat". I agree, it's a great coating. Nothing else comes close to it in terms of reliability. Very few returns. It's the only multicoat I feel truly confident to dispense without fear.

[Memoir]

Hi all,

Australian convention for Hoya's premium multicoat "Super High Vision" is "Super Final Touch" (i.e., "SFT") coating! Which shares the same Hoya recommendations for cutting a VP multicoat.

i.e., Clean front and back surface with acetone, apply multicoat sticker (single sided adhesive cut out, similiar to a tough sticky tape) on both surfaces, block with leap pad and cut within 1 hour.

Additional things to consider are the arm coming down too heavy on the lens and the wheel can't edge quick enough.

• New Nidek edgers have a 'soft setting', which smoothly retracts the wheel as it is edges and then re-engaging. This repeats until edging cycle finishes (similiar to ABS brakes: applying the brakes in small amounts at a time)
• Increasing blocking pressure (at risk of crazing multicoat on and around the blocking area for certain materials if pressure too high)
• Increasing wheel speed to reduce lens drag (at risk of increasing lens burn)

... Or get someone else to fit it! :P

regards,
-Memoir

[Murray O'Brien]

Memoir,
Thanks for clearing up the Hoya terminology for me. Your knowledge of Hoya product is amazing!!!!
One more thing about edging super hydrophobic lenses. Always use the biggest diameter block possible. Small blocks + VP coat + high minus + phoenix = off axis (always). Only way to avoid slippage in this case is cut, re-block then finish. Better solution is to specify 1.6 or 1.67 index rather than phoenix for high minus. High prism + phoenix + VP coat also = off axis and big headache!
B.T.W. I still get the odd job coming my way because a certain lab can't edge it's OWN lenses on axis due to the slippery nature of it's own coating!

[Murray O'Brien]

Memoir,
By the way, I use all the recommendations you advise. The acetone thing has helped a bit, but has not entirely solved the problem.