# Optical Forums > Ophthalmic Optics >  Tinting CR-39 Before UV-NV?

## Randal Cheek

I had a thought after ruining a poly lens during tinting. The failure started with a small clear dot and just began scratching off further. The obvious solution, for me, was to remake them in plastic...because of the previous failure, I have considered tinting the unedged lenses before finishing. Then just hardcoat after to increase durability but not hinder tinting darkness...Please let me know if this is recommended, or whether it will help/hurt the final product, and why?

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## ml43

Spin or dip coating?

spin coat maybe, dip coating runs through an ultra sonic before it is coated, and will alter the color.

I do ar coated tinted lenses all the time.  
Comes out really nice, until you have to tint match 



as for tinting poly before coating of any type.  poly will not tint by itself, when you tint poly, you are actually tinting the coating and not the lens substrate it self.

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## Randal Cheek

Its a spin coating..we use an Ultra Optics Mini II.. I realize that its only the coating on poly that tints....makes it hard to do a good looking gradient or even get much above 60% darkness..The new cr39 lens I'm using is factory hardcoated on the front surface (not sure if its tintable) so I wanted to try to get a darker tint by tinting first and finishing with a hardcoat....I wasn't sure if it even makes a difference as to how dark you can get a plastic lens after its coated...So does anyone know if it behaves the same way on plastic as it does with poly, perhaps only tinting the coating and preventing max darkness in plastic? Or does it behave different on plastic, penetrating the coating and continuing to tint the cr-39 substrate below? If the ladder is true than I'm working too hard  lol =-)

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## MakeOptics

> Its a spin coating..we use an Ultra Optics Mini II.. I realize that its only the coating on poly that tints....makes it hard to do a good looking gradient or even get much above 60% darkness..The new cr39 lens I'm using is factory hardcoated on the front surface (not sure if its tintable) so I wanted to try to get a darker tint by tinting first and finishing with a hardcoat....I wasn't sure if it even makes a difference as to how dark you can get a plastic lens after its coated...So does anyone know if it behaves the same way on plastic as it does with poly, perhaps only tinting the coating and preventing max darkness in plastic? Or does it behave different on plastic, penetrating the coating and continuing to tint the cr-39 substrate below? If the ladder is true than I'm working too hard  lol =-)


If you have a true hard coat, plastic won't tint either.  You could tint before hard coating, but then you run the risk of the hard coat crazing and peeling.  I hate to be the bearer of bad news but you can train your clients to always go for the polarized by upping your price on tints closer to polarized so the difference isn't exorbitant.  This method also makes sense in the present day and age since many lenses come hard coated, or accept various levels of tint, what once used to be an easy 5 minute job is a mine field and so the price should reflect that.  I have worked with opticians that have said that this method is crazy and it's the equivalent of gouging, but time after time I have not been able to make dollars or sense of a low price tint, tint jobs 80% of the time cost more than a polarized either in labor, material spoilage, time, or customer service.

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## Randal Cheek

Thanks Harry, I think that answers my question..I ended up taking the long rout and tinted uncuts first and hardcoated after...looks like they turned out great, but only time will tell lol! I'll keep the polar option in mind for the future...its allot more feasible now with Younger's new gradient/polar product!...This was a purple gradient match job so that wasn't an option...BTW thanks for your opticians.cc site...its been very helpful in our office..

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## MakeOptics

> Thanks Harry, I think that answers my question..I ended up taking the long rout and tinted uncuts first and hardcoated after...looks like they turned out great, but only time will tell lol! I'll keep the polar option in mind for the future...its allot more feasible now with Younger's new gradient/polar product!...This was a purple gradient match job so that wasn't an option...BTW thanks for your opticians.cc site...its been very helpful in our office..


It makes me happy to hear you enjoy the site, a great start to the morning.  I love Younger products, highest quality polar available on the market.

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## anis1975

Hi 
Thank you for your attention. Recently I have baked VU NV coating at 100C for 17h in atmospheric condition after UV curing using a solar simulator. It turned yellowish. When I did Raman spectroscopy on it I did not get any peak, just fluorescence. Do you guys have any idea what can happen to UV NV due to annealing?

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## Randal Cheek

anis1975,

What was the purpose for this test? 100C is more than double the normal conditions for UV NV. What was the substrate material that you used?

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## anis1975

> anis1975,
> 
> What was the purpose for this test? 100C is more than double the normal conditions for UV NV. What was the substrate material that you used?


Hi 
Thanks. The substrate was aluminum coated glass with 30nm SiO2 layer to prevent the Aluminum oxidation. The purpose of the experiment was to study the affect of temperature on the coating. We believe by doing so we can completely cure the sample. But now we are not sure why the sample become yellowish. Can this be more like degradation of UV NV? Also Raman signal become weak with substantial increase of fluorescence. Please let me know your opinion. Thank you. Best regards
Anis1975

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## anis1975

We believe that UV NV is not totally cured upon exposure to UV radiation. If we put another coating layer on the top of it, which needs curing it crazes. To remove such crazing we intend to anneal it to remove the stresses. But it becomes yellow. So we assume chemical degradation and conduct Raman. We observe that it fluoresces. Can you please discuss the effect of temperature on UV NV coating?

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## Randal Cheek

I have not observed the yellow color you mention. Although I have not exceeded 50C in lens production. I have noticed that some of our very old stock poly lenses have yellowed.  However I have noticed the crazing when trying to spin on a second coat right away. The crazing doesn't happen when UV NV is applied to factory hardcoats already present on lenses. I know the manufacturer doesn't recommend multiple coatings on the same substrate. If the coating is several months/years old I have had some success with applying a second coating without crazing. I think you have the right idea, I would decrease temp to no greater than 60C. You might also try a longer cure time. Unfortunately the composition of this material is a trade secret. Here is the Safety Data Sheet: http://www.opticalworks.com/download...ing%20MSDS.pdf

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## ml43

> We believe that UV NV is not totally cured upon exposure to UV radiation. If we put another coating layer on the top of it, which needs curing it crazes. To remove such crazing we intend to anneal it to remove the stresses. But it becomes yellow. So we assume chemical degradation and conduct Raman. We observe that it fluoresces. Can you please discuss the effect of temperature on UV NV coating?


why are you trying to thermo cure a UV cured coating?

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## anis1975

Hello, thanks. If we don't cure thermally then coating on the top of UVNV results in crazing of UVNV. 


> why are you trying to thermo cure a UV cured coating?

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## ml43

> Hello, thanks. If we don't cure thermally then coating on the top of UVNV results in crazing of UVNV.


What type of coating are you putting on top of the uv nv?

an easier solution would be to switch coatings.

there are so many coatings available right now, for both spin and dip coat applications.

but you need to know how you want the coating to perform and work with a coating engineer to optimize performance.

be it, tintability, scratch resistance, thermo resistance, thin film adhesion, etc...

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## anis1975

> What type of coating are you putting on top of the uv nv?
> 
> an easier solution would be to switch coatings.
> 
> there are so many coatings available right now, for both spin and dip coat applications.
> 
> but you need to know how you want the coating to perform and work with a coating engineer to optimize performance.
> 
> be it, tintability, scratch resistance, thermo resistance, thin film adhesion, etc...


I am putting some hydrophilic coating that causes wrinkle. I believe UVNV is based on some aromatic acrylic chemistry. Can you please explain the wrinkling? How can we get rid of it without annealing? What is the reasoning for yellowing due to ambient annealing of this coating?

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## Randal Cheek

What is the output of the UV cure lamp you are using? Are you using standard spin equipment like ultra optics miniII with UV cure box? thermo curing is not recommended for this product and it wasn't designed to be used in that manner. Its not surprising that this product would behave incorrectly when used incorrectly. I would stick to extended ultraviolet exposure in order to cure this product. Or as ml43 said, simply switch coatings. Is the hydrophilic coating you want to use thermo cured? If so, switching to a thermo cured hard coat would be essential. When I was processing frontside Multi anti reflective coated lenses and my UV cure box was running too long, the extra heat would cause the AR to craze.....what kind of properties are you hopping for in a finished product, material, coatings, and application? Lots of opticians are on this forum, and I'm sure one of them could make a process recommendation if you'll expand on what it is you hope to accomplish...

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## ml43

> I am putting some hydrophilic coating that causes wrinkle. I believe UVNV is based on some aromatic acrylic chemistry. Can you please explain the wrinkling? How can we get rid of it without annealing? What is the reasoning for yellowing due to ambient annealing of this coating?


I'm not too sure what UV-NV is made of, never worked with it.  
Yellowing of a clear polymer is normally caused by overexposure to UV(photo degradation) or by over exposure to heat(thermal degradation)
both cause the polymer chains to undergo internal chemical reactions.


The wrinkling/crazing is normally caused by the coating/substrate expanding or contracting at different rates. 

If you are dead set on staying with a spin coat application, I would contact SDC, they just acquired LTI which is the leader in spin coat applied hard coating for polymers.  

SDC also makes some of the best dip coatings.

They are normally very helpful with these kinds of problems, it's what they do all day.

I'm sure they'll be able to find a coating that can withstand your thermal needs. 
If not, dip coating is always the preferred method if heat must be applied(i.e. CVD or PVD processes)

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## Chris Ryser

> *The new cr39 lens I'm using is factory hardcoated on the front surface (not sure if its tintable) so I wanted to try to get a darker tint by tinting first and finishing with a hardcoat....I wasn't sure if it even makes a difference as to how dark you can get a plastic lens after its coated...*


Look into our MicroTint system. Latest technology high temperature dyes, and tinted in a Microwave will tint any lens material faster and darker.

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## Randal Cheek

Thats interesting Chris! looks like a cool shortcut for hard to tint lenses....the description seems pretty straight forward, however I couldn't get the video page to load...I'd be interested in taking a closer look at the results...especially the negative gradient...   

http://optochemicals.com/micro_shortdescript.htm

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## Randal Cheek

Chris, ..I think I remember reading about a microwavable permanent anti fog treatment of yours a few years back...do you still have that product?

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## Chris Ryser

> *Chris, ..I think I remember reading about a microwavable permanent anti fog treatment of yours a few years back...do you still have that product?*


Randal ......... We invented it, manufacture and sell it since 2009, but it has never really taken off. Maybe I have to wait until Essilor re-invents it like they have done with other products we came up with, years ago. 

Also see Oakley's latest Prizm Technology. We had it it in 1984, which is long before they ever thought about it.

There are some industrial safety glasses companies who seem to like it, and purchase it on a regular basis. The optical retail in general, these days, does not seem to be  interested.

You can see at: =======>
http://optochemicals.com/paf_antifog.htm

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## Chris Ryser

> *Thats interesting Chris! looks like a cool shortcut for hard to tint lenses....the description seems pretty straight forward, however I couldn't get the video page to load...I'd be interested in taking a closer look at the results...especially the negative gradient...*  
> 
> http://optochemicals.com/micro_shortdescript.htm



Yes it is the perfect solution for hard to tint lenses fast working nice, and does not take up much space.

I just removed the link from my website on that page. It was made by my distributor in Holland years ago. He sold his company and then then the business got closed down a few years ago.

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## Randal Cheek

> You can see at: =======>
> http://optochemicals.com/paf_antifog.htm


The page is blank for me...

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## Chris Ryser

> *The page is blank for me...
> You can see at: =======>
> *
> http://optochemicals.com/paf.htm
> 
> *working now*.


Thanks for letting me know. I checked the original and there was an empty page with everything deleted.    :Stomp: 


I copied it from a backup and it is all there again since early this morning. However it disappeared a few more times and it took me 5 hours to correct it.

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