RTOriginally Posted by RT
Are you telling me that there is some super new hard coat on top of the AR coating which gives an AR coating better scratch resistance ??????
RTOriginally Posted by RT
Are you telling me that there is some super new hard coat on top of the AR coating which gives an AR coating better scratch resistance ??????
The thing is that most AR coatings use a better quality scratch coating like UT or TD2, so that is why there are more scratch resistant that the regular plastic SRC lens. I don't think there is a difference between UT and UTMC, or TD2 and Crizal or Alize. The only difference might be that the AR is hydrophobic, Anti-Static, and/or Oliphobic, so it repels stuff like dirt that can be wiped into the lens; however, I do not know if there is any fact to that.Originally Posted by Chris Ryser
For Life
Having been in the hard coat business for 22 years I do have a little expertise in this matter, and here are some facts:
1) Tintable hard coats.
Are always soft hard coats. The more tintable the softer they get and the more they are liable to scratch.
2) Non tintable hard coats
These are the real good hard coats. They are scratch resistant to the full value.Hard coats can be made to have an equivalent hardness to glass, but this can not be done as a plastic lens flexes with movement, heat of cold and the the coating would craze or delaminate. There are lots of factors involved how far one can go.
3) Hard coats on AR coated lenses
These coating serve purely as a medium to make the AR coating adhere to it because it would NOT adhere properly to the plastic lens. This is contrary to glass lenses where no intermediate is needed.
4) AR coating
Application of SIO2 in vaccum chamber (basic coating material)
5) Hydrophobic coating (over AR coating)
a) can be applied by evaporating the so called pill in the vacuum chamber when applying the AR coating. Thsi process seals the surface of the AR coating.
b) can be applied after coating by dipping in hydrophobic solution to seal surface and create a slippery surface which can contain also anti-stat and anti-fog features depending on product.
There is no anti-scratch coating applied over the AR coating at this time by anybody.
All in all as mentioned before by many others, the quality of an AR coating depends on how good the hard coat adheres to the lens and then has a good hold on the AR coating. Otherwise these coatings are all made with the same materials under vacuum. The only difference between one and another is the durability of the coating.
I agree Chris, I am just stating that there pretty much is no difference between and AR coated and a non-tintable Hard Coat lens (except if the AR coating is a poor one), and that you can acheive a very good scratch resistant lens without AR.
Chris, perhaps we need Peter Z to explain better, but the assumption that the abrasion resistance of a lens is solely a function of the extremely thin AR layer is false. The AR layer is nanometers thick, yet the scratches you see in an AR coated lens are deeper than that--they go into the substrate. The fact of the matter is that the performance of the AR coat depends upon the properties of the substrate for more than just adhesion.
You've also made a (bad) assumption that the AR stack on the newer coatings is identical to the AR stack on older coatings. The AR stack itself is different on Super HiVision than on HiVision, and on Crizal Alize than on Crizal. Differing thicknesses of the layers implies differing hardness, thermal properties, etc. Note that they have different AR properties as well as different abrasion resistance.
You've made your point about coatings using SIO2 before. Doesn't make it true. If similar ingredients were all it took to be successful, then BAM! I can cook like Emeril Lagasse simply because I can buy spices.
RT
I have not yet had Crizal or Crizal Alize fail. I have had HOYA fail in a relatively short period of time. Simulated tests and the real world are not always the same.
How many 89 year old patients do you have?Originally Posted by Spexvet
Thanks for your friendly lecture. I am so glad that somebody finally puts me in my little corner.Originally Posted by RT
For the last 22 years I have researched and manufactured optical coatings, sold, and still supply some of the major manufacturers you continously mention as different and better with products in this field.
You can also purchase the spices from me and then cook like Emeril but only after you have studied the cook book. :hammer:
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Actually most of the time when you have scratches on AR coated lenses they go only as deep as the hard coat which gets marked.
By using an AR strupper you can strip the AR coating and then the hard coat and you are left with the basic lens which most of the times has no scratches whatsover. You have then saved a pair of lenses for further use!
Polycarbonate and ARC do not go well together. I much more prefer the trivex lens material. Yes it can be a little thicker, but for children especially the benefits of the impact resistance of this lens is incredible. I do not personally recommend ARC on childrens lens because they are harder to keep clean.
Sure they do. My last three of my last four pairs have been poly with Crizal and now Crizal D Alize. The other one was Trivex. Maybe you are just getting poly from the wrong source. We do a lot of poly with AR (pretty much only AR). We use the Aspheric Airwear poly lens that Essilor distributes.Originally Posted by Tjcjdc9462
So, do you think plastic is better for people that complain about the lenses scratching too easily? I thought poly was stronger, but wonder about the scratching.
Thanks
..........and the older they get the easier they will adapt.........they wont even know the difference any more at that age. Good Job.Originally Posted by Spexvet
:D :bbg:
I agree, warranties are the real reason kids are being put in AR. I think it is rediculus! I love the newer ARs but they just aren't up to what kids can dish out. DON'T TELL ME THEY ARE, BECAUSE I HAVE SEEN IT AND THEY ARE NOT! I don't mind getting down with some serious education on a high myope on how to take care of their new glasses with AR. Also, I totally agree that tintable coats scratch easier. This information should be marked clearly on the uncut lens packaging. Back surface scratches tend to be due to the way the lens is cleaned such as placing pressure with the thumb while rubbing the lens. I would teach the child to be more gentle while cleaning their lenses and not to bare down with their thumb. No matter what, kids scratch lenses and we just have to get them to the point were the glasses outlast their change in Rx or within reason.
A lens with AR is more scratch resistant than a lens without AR.Originally Posted by SpecialT
I believe this to be true, HOWEVER, A scratched AR lens looks a he** of a lot worse than a similarly scratched non AR lens. Herein lies the problem with patients. They may never even notice the scratch on the non AR lens, but they always notice it on the AR.Originally Posted by For-Life
This being said, I feel many of the curent AR's are very good including their scratch resistance.
you know why all of your patients from Wally*World have AR on their lenses?? because they don't have a choice... it's bundled automatically. Every lens package has non-glare, save one...
there is a non-AR option... but it's waaaaay down in the corner of the consulting mat, in small print "Basic Plastic lenses $xx.xx"
Last edited by eromitlab; 11-19-2005 at 10:52 PM.
they're smartOriginally Posted by eromitlab
then they come to us and we give them less of a value by not giving them AR (hope not, but it emcompasses the general).
well, I think it's also due to the fact that they can make it easier for a register jockey to shift over into the vision center and be able to sell big lens packages by taking the option away from the customer... the customer is always right, so they say... well, that's because they are never given the chance to be wrong...Originally Posted by For-Life
Perfect post.................That's why kids should not be fitted with "Cadillac" type lenses at high cost.................and the optician should be reasonable in pricing so that the kid will be back next time.Originally Posted by SpecialT
i do regular cr39 for kids, and let them upgrade to ar coated lenses once they are grown up enough to look after them. I judge this saying to the parants that when the old spectacle lenses are inspected and in good shape (where the coating would still be in good shape). this gives kids an incentive to look after thier spex, and parants know the coating is only a nominal fee, once the kids have looked after thier spex
It is my understanding that the WalMarts around here offer a Poly with A/R as standard with their children's package. I have had many folks come in with a walmart a/r that was ruined after just a few months. I have been told they use a Zeiss coating.Originally Posted by April_01
I agree that an A/R (a quality A/R with a good warrantee) should be offered to children. Some of these kids are going to have brand new cars at 16, expensive summer camps every year, and all the latest and greatest brand name clothes. Why should we refrain from giving them all the options and prices? Let the parents decide. An a/r has all the benefits for children as for adults (with the exception of improved night driving), so why not offer it?
As for scratch resistance, I would take a shv, alize, or other similar lens over a stock poly of sr CR39 any day of the week for longevity.
AA
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