# Optical Forums > General Optics and Eyecare Discussion Forum >  Recipe to remove worn out AR coating

## spexwala

Hi,
Does any one have the recipe to remove worn out anti reflection coating from CR39 lenses?
If we opticians have this in our office,this will reduce the burden on the prescription lab,reduce the waiting time for the patient,& will make the patient happy,who has paid a good amount for ARC lenses,& has got it scratched.
I think it is resonable to decoat the lenses,for a complaining patient.
Any one??????
Any comments???????

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## jofelk

AR stripper is available from optical lab suppliers. The solution is easy to use.
A small plastic food storage container and a pair of wooden tongs (from the company that supplied the AR remover). Let the lense soak for a few minutes.
   BEWARE: glass, polycarb, and high index may not be possible to strip.

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## Cindy Hamlin

At your local craft store you can purchase armor etch (or bath).  It is made for etching glass so can be used on all materials except glass.  It costs about $8-$13 a bottle.  The armor bath lasts the longest as you soak the lenses in it and can return it to the bottle when done.  It has worked well for us in the past.

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## chip anderson

Note Armor Etch is phosphoric acid,  very dangerous handle with care, on skin it makes a sore that does not heal.  In the eye, I shutter to think what it can do.    Read and use the precautions (especially protective gloves) .

Chip

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## Cindy Hamlin

> *chip anderson said:* 
> Note Armor Etch is phosphoric acid,  very dangerous handle with care, on skin it makes a sore that does not heal.  In the eye, I shutter to think what it can do.    Read and use the precautions (especially protective gloves) .
> 
> Chip



Yes, Chip, on the label it says to wear gloves.  In all the years we have used it there has never been a cause for harm from it!

Then again, isn't the AR stripper an acid as well?

Here is the link to the armor etch MSDS sheet:

http://www.artglassbiz.com/msds_sheets/1002.txt

And here is the link to the MSDS sheet for the AR Stripper:

http://optochemicals.com/msds/msds_ar_stripper.htm

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## Chris Ryser

I invented the AR stripper in 1984 and can help and advise fully on this subject.

It takes 10 seconds of immersion at room temperature for removal of an AR coating. Easy!

Send me an e-mail and I will give you the answer.

I advertised in one of the trade magaziunes at the time and received a letter from one of the large lens coating companies that AR coatings would not have to be removed as they where permanent, and that they would have to sue me for false advertising.

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## Chris Ryser

> *Cindy Hamlin said:* 
> Yes, Chip, on the label it says to wear gloves.  In all the years we have used it there has never been a cause for harm from it!
> 
> Then again, isn't the AR stripper an acid as well?


Cindy,

The AR Stripper is a mix of acids and solvents. The newest version contains 9-10 % acids only, but removes an AR coat on 10 seconds.

The material has to be kept closed at all times when not in use as the solvents tend to evaporate and the acid mix is to weak to work alone.

AND YES.....................when handling chemicals, always make sure to be protected.

The oldest formula to remove AR coatings used to be a mix of sulphuric and boric acid and it had to be heated. When too much heat was applied it exploded.  Not too many coating labs are still doing this one.      But protection should always be there.



:finger:

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## Jim G

I've used Chris' stuff and it works well and doesn't have a particularly noxious odor; can't say that for phosphoric acid.

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## kcubb

Is there a formulation for removing the coatings from 1.67 seiko lenses (MR-10 resin)?
Thank you in advance.

Regards,

kcubb







> I invented the AR stripper in 1984 and can help and advise fully on this subject.
> 
> It takes 10 seconds of immersion at room temperature for removal of an AR coating. Easy!
> 
> Send me an e-mail and I will give you the answer.
> 
> I advertised in one of the trade magaziunes at the time and received a letter from one of the large lens coating companies that AR coatings would not have to be removed as they where permanent, and that they would have to sue me for false advertising.

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## Chris Ryser

> *Is there a formulation for removing the coatings from 1.67 seiko lenses (MR-10 resin)?
> *



I really don't know how MR-10 material stands up against hydrofluoric acid, which the one acid that does the dissolving of the AR (SIO2) layer.
In that case you only dip the lens for 1mm at a corner for a second or 2. If the material turns milly white you can remove it on a hand edger.

If you are using an AR stripper that is sold in a powder form ( hydrogen fluoride) and you add water, it becomes the most dangerous acid (Hydrofluoric) existing, and you should be totally caerful with it.

Hydrofluoric acid is a highly corrosive acid, capable of dissolving many materials, especially oxides. Its ability to dissolve glass has been known since the 17th century, even before hydrofluoric acid had been prepared in large quantities by Carl Wilhelm Scheele in 1771.[2] Because of its high reactivity toward glass and moderate reactivity toward many metals, hydrofluoric acid is usually stored in plastic containers (although PTFE is slightly permeable to it).[3]
Hydrogen fluoride gas is an acute poison that may immediately and permanently damage lungs and the corneas of the eyes. Aqueous hydrofluoric acid is a contact-poison with the potential for deep, initially painless burns and ensuing tissue death. By interfering with body calcium metabolism, the concentrated acid may also cause systemic toxicity and eventual cardiac arrest and fatality, after contact with as little as 160 cm2 (25 square inches) of skin.

Out of above reason  we developed a stripper that only contains 3-4 percent total of an acid combination to minimize actual immediate dangers.

check at ------------->   http://arcoatings.com/ar_%20stripping.htm

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