Bear in mind I'm in the UK. I swear the rep was trying to sell me Shamir coatings. Weird. So, in the US/Canada, do Shamir only sell semi-finished?
We deal in primarily Crizal and Hoya, Correct me if I'm wrong but I have been led to believe that Hoya is the only company that does substrate matching so you wont get the newton ring effect that you get with other companies. Appears to be most noticeable on 1.74 from my experience.
I believe Hoya is the only company to actively market their substrate matching prowess. It's been ages since I've seen any of ol Newt's rings in any of the higher quality 'name brand' A/R's myself. I think the bigger overall push of the last five years or so has been improved abrasion resistance and enhancing the oleo/hydrophobic properties of the top tier offerings. Customers get that - though I expect you'd be hard pressed to meet many consumers who know about (or indeed even care about) the possibility of slight rings in their A/R when being looked at. I'm guessing the blank stare you'd likely get as you tried to explain it in many cases might cost you the upgrade...
The newton rings are caused by Hard Coats and AR processes with an ABBE value different from the base material... and not solved by Substrate Matching.
Hard coats come in two flavors, tintable and non-tintable, one each for every material in a perfect world. But we don't live in a perfect world. Hard Coat laquer is very expensive and unstable, so we live in a cost effective one. So most small and medium labs compromise, they either carry 2 or 3 indexes only, tintable only. The result is birefringence when they don't match ABBE value. Very few labs are big enough to have every hard coat, in every material available. Its why most high end AR's are still outsourced, as is 1.74.
Hoya is not the only company to offer substrate matching. All it means is that the Hard Coat is matched the the base material. nothing more. Its not really magic, Hoya buys most of their hard coats from Matsui Resin company of Japan, so anyone has the capability to do it. We once lived in a world of one great hard coat, but that changed a few years ago. More high end ARs are made with Hardcoats matched to the base material.
Don't believe the marketing hype, its just simply having more vats of good hard coat available. Its not really a technology per se.
I think you mean "refractive index" not "Abbe value." Interference fringes result when there is a difference in refractive index at the interface between two materials, particularly when there is a variation in coating thickness.Originally Posted by sharpstick
Best regards,
Darryl
Darryl J. Meister, ABOM
I really do like Hoya's coatings. EX3 in particular. I did however want to throw something out there: when our Hoya Rep was telling us about their coatings (even though I was already sold on them), she told me what set Hoya's apart from others is that they are all substrate-matched. This confused me because I always assumed that everyone did that; my understanding of how AR worked was that the coating index must be the square root of the substrate index. Now, because I don't and never have worked in a surfacing lab, I never verified this. She told me that all other coatings had one formula that they used for all substrates. This made me feel a little stupid because I had never thought to look into it. What is the deal? Any input from the lab rats?
Edit: I just realized that this question was already posted in this thread. Sorry... But I'd still like to get more opinions.
Last edited by musicvirtuoso; 01-15-2013 at 09:22 AM.
Rumor mill says Shamir created their AR stack using satis chemistry and tech. When E bought satis they effectively stopped the release of Shamir AR in the US, but it has been available in the EU for a while.
Again this is rumor mill, but I heard it from what I consider very reliable sources and yes that's source with an s so I am inclined to believe it.
Actually there are now products available with which you can very simply renew the "Easy Clean" properties out of a spray bottle at very little cost. So the problem is solved that way.
Now you can actually use any type of AR coating, expensive, or cheap, and give or sell your patient a little bottle of the topcoat and problem is solved.
I like Zeiss Purecoat. Do not use it on a ft bifocal.
build up at the segment line. They use allure to help with that, but I have stopped ordering FT's from zeiss as they all come with a puddle across the seg. my local lab knocks it outta the park in that area. comes in perfect.
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