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Thread: Bayer Abrasion Scale

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    OptiBoard Professional skirk1975's Avatar
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    Bayer Abrasion Scale

    How accurate is the Bayer abrasion scale. I saw some stuff from Hoya that a normal old AR has about a 2 out of 12 rating. Glass has a 12. There Super Hi-Vision was like a 10 or something. It is almost as tough as glass ??? Is this scale accurate ??? Alize' only had a 5. I think Teflon was 6. Higher than Alize'. Who has thoughts on this. And also is there some type of absorbtion scale for water ???

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    Allen Weatherby
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    Testing methods can be misleading many people assume that in a test such as the bayer test that the higher number is better and generally this is true, however when you mention the test for Alize vs. teflon (name licensing is a wonderful thing), you might not want your hydrophobic to be super hard but rather actually do what it is intended to do and that is repell water and fill in the rough surface of the AR. No one tell you in there marketing materials how rough their AR surface is or how dense. Yes some are more dense than others, and how these are covered with a hydrophobic, and how is the hydrophobic bonded?

    You might try testing a sticky note to see if it adhears to the lens surface. Now take a piece of regular scotch tape on the hydrophobic, press firmly then pull it off. Do this up to 10 times on the same place, and now see if the sticky note still comes off as easily? Many hydrophobics do not have a good chemical bond a few do. Guess what the ones with the great durability vs the ones that don't last cost the coater different prices, so when the optical retailer orders the product and like the majority they want the lowest price possible the way to make them happy is give them the lowest cost item so the lab can still make a buck. You do get what you pay for in a lot of cases. There are some exceptions. Deal with honest ethical companies, let them make a fair profit and use their resouces to help you.

    My point is your question regarding the Bayer test is not a simple answer and in your own question you are attempting to measure hydrophobic coatings with the Bayer test which is actually measuring the underlying hard coat as the hydrophobic is so thin and slick that I doubt that you get any good information about the hydrophobic with a Bayer test. I have never considered the Bayer test as a test for a hydrophobic.

    Any one else have an opinion who actually test hydophobics in a meaningful way?

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    Allen Weatherby
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    One more item regarding Bayer tests. If a test is performed on the front surface of a semi finished lens and then these lens is surfaced at different labs the back surface results will vary from lab to lab and a Bayer test can not be easily performed on the back surface. Does your lab have an excellent hard coated lens they purchase then surface? Then do they put the same quality hard coating on the back? I doubt it, very few do. Then you have the same AR applied to two different hard coated surfaces and the durability will all most always be different for the front to the rear surface. What saves the industry from this being a bigger concern is the fact that most rear surfaces are concave and in the frame rarely contact other surfaces.

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    Manuf. Lens Surface Treatments
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    Redhot Jumper Only a seal.........................

    Quote Originally Posted by AWTECH
    Any one else have an opinion who actually test hydophobics in a meaningful way?
    Actually there is no such thing. The manufacturers buy the material to do the job from very few suppliers and do the application each one their own way. After that each one claims that his own way is the best.

    Hydrophobic coating have nothing to do with sccratch resistance, they seal the surface against dirt penetration and make the lens easier to clean.

    I invented hydrophobic coatings in 1986 and have never even heard of any standards in testing and dont think any are necessary. The technique is only there to seal the AR coating surface.

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    OptiBoard Professional RT's Avatar
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    The Bayer abrasion test has proven to be an accurate predictor of real world resistance to abrasion. Coatings and materials that score higher on this scale don't scratch as easily as lower scoring coatings and materials.

    I don't believe, however, that the results are linear. That is, I don't believe that a coating that scores 10 is twice as hard as a coating that scores 5. Small differences in Bayer rating are probably not particularly significant. Since many people are extremely satisfied with the durability of coatings that have achieved 5 or 6, one might say that they represent an acceptable level of durability.

    Note that the Bayer test reports an average of multiple lenses tested. If a manufacturer has problems with the consistency of their process, it is possible that they will produce lenses of higher or lower Bayer rating--meaning you can still receive a high rated coating that scratches easily. I don't know of any way to quantify the consistency of a process. Your experience will have to be your guide.

    AWTECH raises some questions about comparing the slickness of the newer hydrophobic coats. While I'm not sure that those questions address the original inquiry specifically about Bayer testing, there is one clarification that needs to be made. HOYA's Super HiVision is not just a slippery coat on top of their more traditional HiVision coat. SHV requires a completely different recipe, takes longer to produce in the AR chamber, and happens to incorporate a super-slippery top coat. While these top coats do enhance a coating's ability to resist abrasion, SHV's durability stems from the entire process, not just the hydrophobic coat. Because of the juxtaposition of the questions about slipperiness with the Bayer question, one might not understand the distinction.

    All HV and SHV lenses employ a thermal cured dip coat hardcoating process. As such, they have the same abrasion resistance on front and back, even when the lens is surfaced.
    RT

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    Manuf. Lens Surface Treatments
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    Question....................

    Quote Originally Posted by RT
    All HV and SHV lenses employ a thermal cured dip coat hardcoating process. As such, they have the same abrasion resistance on front and back, even when the lens is surfaced.
    After thermal cured dipcoat is applied with the usual thickness of about 2 microns............................

    How do you explain that the lens retains the same backside abrasion resistance after the lens has gone through a surfacing process by taken off a lot more material than the thickness of the hardcoat?

    Obviously the hard coat has the been removed................what then makes it retain the same abrasion system as the front?

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    Objection! OptiBoard Gold Supporter shanbaum's Avatar
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    Trick Question?

    Quote Originally Posted by Chris Ryser
    After thermal cured dipcoat is applied with the usual thickness of about 2 microns............................

    How do you explain that the lens retains the same backside abrasion resistance after the lens has gone through a surfacing process by taken off a lot more material than the thickness of the hardcoat?

    Obviously the hard coat has the been removed................what then makes it retain the same abrasion system as the front?
    Wait... let me guess... I bet the treatments are applied after the lens is surfaced!!!

    How'd I do?

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    Manuf. Lens Surface Treatments
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    You just won..............................

    Quote Originally Posted by shanbaum
    Wait... let me guess... I bet the treatments are applied after the lens is surfaced!!!
    How'd I do?
    Shanbaum........................You just won the first price......unless somebody objects.

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    OptiBoard Apprentice Trevor D's Avatar
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    Quote Originally Posted by AWTECH
    ?

    You might try testing a sticky note to see if it adhears to the lens surface. Now take a piece of regular scotch tape on the hydrophobic, press firmly then pull it off. Do this up to 10 times on the same place, and now see if the sticky note still comes off as easily?
    In our store we use scotch tape to remove the progressive lens markings instead of using acetone (when methylated spirits will not clean them off). Is this damaging the AR/Hydro coating? Are we actually peeling off the hydrophobic coating by doing this???

    TD

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    Manuf. Lens Surface Treatments
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    Same thing.....................only thinner

    Quote Originally Posted by skirk1975
    How accurate is the Bayer abrasion scale. I saw some stuff from Hoya that a normal old AR has about a 2 out of 12 rating. Glass has a 12.
    Your top layer is alway's SOI2 (silicone dioxide) which is glass. Would make sense that it gives about the same results as glass, but very thin and therefore maybe not as resistant due to the softer lens surface underneatth.

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