Tinting Poly?

[Corey Nicholls]

Can anyone give me any hints on tinting poly? The advice I have been given (You may have guessed that we don't get much call here for tinted poly) is that it does take longer to tint than CR39, and that it cannot be kept in the tint too long because the heat may ruin the lens. The same person who gave me this advise, also said that it is impossible to achieve a dark density.

The job this relates to is for a sports shooter who requires a rather heavy yellow tint, with multicoat, and I have been told by Sola that it is impossible. Essilor here in Australia says that they won't even attempt to tint poly at all!

Is there a certain brand of tint that will work better than others for poly?

All feedback will be appreciated. :)

Corey.

[Alan W]

Corey
Finished lenses or semifinished lenses generally have a scratch coat that locks out tints. There was a time (less so now) when uncoated poly could be tinted and then a spin coat applied after surfacing or a tintable spin coat was used. I need someone to clarify that because its been a while since I've been in the lab environment. Unless we both hear differently, the issue of tinting poly remains as you've experience it .. no can do . . much or at all!

[so]

Vision Ease advertises one of their finished lines as being tintable (Allegra I think). Poly usually tints very quickly, but doesn't get very dark. You must be carefull to use a neutralizer specifically for poly, but don't let the lenses sit in the the neutralizer. Do not use regular neutralizer, the finish will craze.
Some poly products such as Sola's Fisher Price will not tint at all.

[chip anderson]

This is a been told but don't know from personal experienced. Add a few drops of detergent to dyes, this lowers the wetting angle. Makes things dye more easily.

Chip

[Matthew]

For Poly I standardly use Gentex Stock and Semi finished product as well as Vision Ease and have no problems with the tint or coating.

[Jim G]

There is an inverse relationship between tintability and hardcoats. The harder, the less tintable; conversely, the more tintable, the softer the coating. The older polys were all somewhat tintable; a sort of compromise. About 5 years ago, manufacturers brought out harder, non-tintable coatings (VE; On-Guard and then Tegra. Gentex, GLC). These, obviously, won't get very dark. Concommitently, they also came out with more tintable coatings (VE; Allegra.)

The above is for finished SV. Semi-finished blanks require a lab applied backside coating. These are also available in harder, non-tintable form but, more commonly, are reasonably hard and very tintable.

So, the answer to your question rests primarily on the lens blank that you are using.

Some hints on tinting: Ensure tint bath temps of at least 98C and make sure the dye is new. Given you're using a tintable coating, gray 3's are very attainable.

[Corey Nicholls]

Thanks everyone for your advise it is very much appreciated. :D

I have checked with supplier on the availability of Gentex brand lenses and found that I can get them, and yes they are easily tintable- "The Easiest" I was told! The problem was that the two main multicoating facilities are owned by either Sola or Essilor. Sola will only coat their own product (which is not tinted easily), and Essilor will not tint any poly.

I have managed to track down an independant supplier who can source Gentex and have their own multicoating, but their multicoating I don't trust. I suppose something is better than nothing though!

Again many thanks Corey. :) :)

[sgreen]

Corey, I believe that Essilor owns Gentex...there should be no problem with Essilor coating Gentex product.

[Corey Nicholls]

That's interesting! They told me they could not do it. Maybe the problem is that Gerber Coburn distribute it here, and Essilor may not.

[Alan W]

Corey
Yesterday I ran 7 jobs using Gentex Poly, three were tint jobs. None would darken beyond #1 density except on the edges where there was no coating after finishing. BPI dye, 205 degrees right off the Essilor tinting manual.
I have never been able to tint Gentex stock darker than #1 density in less than 1 hour in the dye.
I am having a problem with the claims they made unless they have a deep dark secret (got the double entende?)
Semifinished is a no brainer. There's no hard cote on the back side . . . duhhh!

Uhhhh . . . Am I doing something wrong?
Maybe I should soak the lenses in Kosher salt, or maybe meat tenderizer. Better I should call Emeril . . . he'll kick it up a notch.
BAM!

[Jim G]

Alan, I gotta ask the obvious, are you using the tintable vs. the GLC brand?

As I noted in my post above, polycarbonate is virtually untintable and requires the coating to absorb the tint.

Have you tried other brands? I have personally tinted poly to <20% transmission so I know it can be done (altho it wasn't Gentex).

[Alan W]

Jim G
That's it! That's my problem.
Boy, am I a dum kopf!
I'm using GLC.
Duuuuuhhhhhhhh!
Thank you thank you thank you.
mwuh mwuh mwuh!

[stephanie]

Can't a surfacing lab impregnate the tint? All you are doing with a stock lens is tinting the coating which will not get too dark and can craze very easily. I am not too sure about the impregnating tint someone else may want to clarify this, but I think it can be done. Any thoughts???
Steph

[Jackie L]

BPI makes a dye specifically for polycarbonate lenses.

Jackie O

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Still a Maina for now

[Jim G]

Geez Steph, I'm way too old to impregnate anything let alone a poly lens.

Uncoated poly is essentially untintable (is that a word?) using standard techniques. All the tint is absorbed by the coatings. At the lab level, the backside coatings we use are typically pretty absorbant and will allow a poly lens--even one with a hard, non-tintable front coating--to get to a tint 3.

There are tintable finished lenses out there but, as mentioned before, the more tintable, the less scratch resistant. The manufacturers formulate a coating that they feel offers a good compromise between the two. And, the coatings have progressed significantly over the last 5-8 years.