problem with mirror coating

**Aarlan** · 08-25-2010, 12:32 PM

Hello all,

We have an repeat customer that we make a special combination lens for on a regular basis.

We take a Transitions Progressive, send it out and have a gradient tint applied and then a Mirror coating applied to the front surface. It allows a very slight hint of color in the lightened state, but when it changes to dark it is a perfect mirrored sunglass...pretty cool. The mirror coating often matches the frame (generally zyl ).

My issue is this. We have done this a total of 5 separate times. sometimes it works magically, others awfully, even with the same combination of lens, tint and mirror

We have had an issue where the mirror was too dense and it seemed to reflect equally off the back of the lens. We had them strip the coating and reapply it and it came back just fine.

We just did another one (a green mirror) and the reflection is ALMOST as reflective as you are looking out of the lenses as when you are looking at the lenses. THe demo lenses that came in their kit do not have this effect.

WHat am I missing? why would the reflectivity as you are looking out be noticeable more on one pair than another, even with the same lens, tint and mirror combo? Is it applied incorrectly?

**MikeAurelius** · 08-25-2010, 02:59 PM

My experience with mirror coatings has been as varied as yours has been -- and it all seems to come down to who is running (and programming) the coater. The experienced hands can do repetitive coats over time and they all turn out identical. Get a n00b in there and it all goes to hell.

I've found that if I call and talk with the manager about it, when I send the job in for a re-do, it's given to the 'old hand' and it comes out perfect.

**Aarlan** · 08-25-2010, 05:07 PM

The other problem we have had is that on the occasion that we stripped and recoated the lenses, the lenses crazed w/in weeks, but when the lenses were remade and coated we had NO crazing issues. Is there something in the stripping process that lingers or interferes with the application of a thin film?

**Aarlan** · 08-25-2010, 05:08 PM

I was expecting Lee P or Chris Ryser to chime in ....come on guys I thought you spent 9 hours a day here!!

**Peter Z** · 08-25-2010, 08:50 PM

Stripping is a harsh process using acids that attack not only the AR coating but also the hardcoat. We don't recommend stripping lenses but if it has to be done you must remove the hardcoat and have it re-applied along with the mirror and or A/R coating.

**Chris Ryser** · 08-26-2010, 04:08 AM

Originally Posted by Aarlan

The other problem we have had is that on the occasion that we stripped and recoated the lenses, the lenses crazed w/in weeks, but when the lenses were remade and coated we had NO crazing issues. Is there something in the stripping process that lingers or interferes with the application of a thin film?

Actually, when stripping the lenses, the stripper contains anywhere from 1 to several acids. There are always some acid residues left in porous lens surface.

These acid residues have to be neutralized before recoating, or the lenses will do exactly what Aaarlan describes in his post.

However while sales of AR Strippers have increased in our business over the last 2 years, the use of the acid neutralizer, has remined very stale and I suspect that many coaters refrain from using it and therefore lenses will craze again after a redo job..

**Chris Ryser** · 08-26-2010, 04:28 AM

Originally Posted by Peter Z

Stripping is a harsh process using acids that attack not only the AR coating but also the hardcoat. We don't recommend stripping lenses but if it has to be done you must remove the hardcoat and have it re-applied along with the mirror and or A/R coating.

I would like to correct above statement with your permission.

When you work with straight acids mixed to your own formula, this can happen. However if you use a premixed version that has a controlled acid content of only 11.5% mixed with some solvents, your stripping time is between 5 to 10 seconds before you attack the hard coat.

Therefore stripping the hardcoat is not required, if not needed due to scratches.

It is so easy to strip AR coatings safely, even just on old lenses to be used as is, as some backup glasses or sunglasses without any scratches that were situated in that hard coat.

**Aarlan** · 08-26-2010, 04:00 PM

One of the reasons that I use the coating lab that I do is that they offer a variety of lens mirror colours, but if we keep having to remake them, I'm going to have to change mirror labs. Problem is that many of the mirror labs that I would work with either do not allow transitions w a tint as the lens to be mirrored, or they have limited colours avail.

ICOAT would be my first choice, but no Green mirror.

As for the increased back coating, the lab told me that there should not be any variation in coating, and that the backside reflection is just something that happens...why on earth would it not happen with the demonstration lens then? I'm going to send them the demo and the job they did and ask them to make it work...I'm annoyed.

**Aarlan** · 08-26-2010, 04:01 PM

by the way, I knew you would come to rescue on this thread Chris...thanks

**Mirror Man** · 03-11-2011, 08:32 AM

Stripping has the potential of harming the hardcoat as it is a very important layer when we talk about adhesion of any coating applied to the surface of the hardcoat. Any coating failure after stripping is most likely due to adhesion problems.

**Lee Prewitt** · 03-18-2011, 05:51 PM

Originally Posted by Aarlan

One of the reasons that I use the coating lab that I do is that they offer a variety of lens mirror colours, but if we keep having to remake them, I'm going to have to change mirror labs. Problem is that many of the mirror labs that I would work with either do not allow transitions w a tint as the lens to be mirrored, or they have limited colours avail.

ICOAT would be my first choice, but no Green mirror.

As for the increased back coating, the lab told me that there should not be any variation in coating, and that the backside reflection is just something that happens...why on earth would it not happen with the demonstration lens then? I'm going to send them the demo and the job they did and ask them to make it work...I'm annoyed.

Aarlan,

Better late than never right? I must have missed this thread last summer. Your issue may be a lack of a backside AR. Our mirrors are standard with back AR. You can get a nasty reflection even with a flash mirror if you do not have the AR included. Last summer we did not have a green but good news! We now have added Green, Black, Cobalt, Red and Pink to our family of ICE Mirrors. Would love to talk to you about your mirror needs. Perhaps Monday?

**Mirror Man** · 03-21-2011, 07:29 AM

Responding to Aarlan's thread flash mirrors are the correct choice for Transition,Drivewear type lenses in the market place. A flash coating or a clear mirror coating will not interfere with the performance of the lens. The good folks at Transitions and Drivewear have tested this and have found that performance does not suffer at all. A tint will inhibit the lenses ability to change as they are designed.  Plus I wear them personally and the coatings give you just a little extra in dealing with glare and blinding sunlight. Any ECP who knows that their customer is going to wear these types of lenses  for sunwear would do their customer a great service in recommending this add on . Flash Gradients are also a great touch.

Check out the mirror colorations offered by OPTICOTE via this link.....<br>http://www.opticote.com/mirror-coati...ml   I am sure you'll a coloration to match your customers  personality and lifestyle.<br>