ASK THE LABS
By Joseph L Bruneni

Standards for AR Coatings

Q I've heard that the AR coating industry was trying to establish Industry Standards for AR Coating. Has this been established and are they published? Is there some kind of "Good Housekeeping" seal of approval on coatings?

A We checked with two sources on this interesting question. Our first source was Grady Culbreth, past president of the AR Council. She reports that the Council has been working on this complex subject for several years. What they have produced are not standards but represent standardized test methods that AR coaters have agreed are ways to test the AR coatings they produce. Half of the test methods are completed, and the rest should be completed in the next six months. Once they are finalized you will be able to find them on the Council's Website (www.arcouncil.org). Additional test methods will be added to the Website as they are completed.

Since none of these test methods has been subjected to a formal field correlation study, the AR Council has not determined whether these test methods should or should not be considered reliable. They are being published so that members can decide for themselves if they wish to use them. The advantage of them is that all coaters will be using the same protocol for testing their coatings. Establishing test methods accepted by all Council members also makes it possible for each member to reproduce the tests in their own lab. Test users may also find that no one method can provide sufficient information to evaluate an AR coating. A combination of three or more test methods may be necessary to provide adequate evaluation of AR coating performance.

John Young, president of COLTS Laboratories, a testing facility in Clearwater, Fla., points out that there are several third party or independent assessment organizations for consumer goods. Consumer Reports publicizes results it finds in testing of products but offer no seal of approval. Good Housekeeping does not publish its confidential test results but does offer a seal of approval for products that meet criteria set by them. AR lenses may not currently be part of their list of goods. COLTS Laboratories offers a Performance Seal similarly to the approach taken by Good Housekeeping but specifically for the optical industry. Several AR coated lens products as well as AR equipment have the COLTS Seal. COLTS Laboratories will provide a list of those suppliers and products to anyone who would like a copy (www.colts-laboratories.com).

Q Would a multipurpose polycarbonate goggle that is suitable for skiing, biking, etc., as well as for use by surgeons and dentists (for protecting eyes from splashing) require industrial safety thickness lenses in order to comply with Z87?

A The requirements for a goggle to provide splash protection are contained in ANSI Z87.1-1989. Minimum thickness for non-glass lenses is 1.27mm and glass lenses must be 3.0mm. All goggles claiming conformance to Z87 must be stamped Z87. For sports goggles, there is an ASTM standard for skiing goggles (ASTM F659). There are no minimum thickness requirements. There is, however, a field-of-view requirement for ski goggles. For skiing goggles, 2.0mm Trivex and polycarbonate will pass the impact tests. For Z87 goggles with non-removable lenses, both Trivex and polycarbonate will pass the test. For removable lenses, almost any 2.0mm plastic lens will pass the test.

-Dan Torgersen, OLA technical director

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