Separating Lenses Bonded
With Norland Optical Adhesive


T
he simplest method for separating a lens bonded with Norland Optical Adhesive is to immerse the lens in a solvent combination made up of the following: methylene chloride, 100 parts by weight -methanol, 15 parts - concentrated ammonia (26 Baumé or 29% NH ), 2 parts. The methylene chloride is the active solvent and the other solvents increase its activity.

A typical 1 inch diameter lens will separate easily before the full cure by an overnight soak in these solvents. A fully cured lens requires a longer soak because the adhesive is more crosslinked and slows the solvent penetrations. Some lenses may start to separate but the solvent does not penetrate to the center even after a long soak. This is due to a very thin layer of adhesive in the center. To separate these lenses a slight thermoshock is necessary. Warm the lens up to 150°F and immerse it in the solvent combination while still warm. The sudden contraction will allow the solvent to penetrate to the center. Repeat if necessary.

Heating in hot mineral oil is another method that is commonly used. Usually it will take 20 to 40 minutes at 400 degrees F for the lens to separate. An alternate heating method is to place lenses in a vacuum coater and heating them under vacuum until they separate. Remove adhesive from glass surfaces now by immersing in the solvent combination.

Large lenses may require even higher temperatures to separate them. One method that has been successful is a heated sand bath at a temperature of 800°F. A fine sand or emery is heated in a pan on a hot plate. When it is up to temperature the lens is placed on the surface and will separate as it heats up.

Paint strippers containing methylene chloride are usually available from local hardware stores and will work as well or better than the solvent combination given. A liquid formula will work better than the gel-type.

Brulin’s Safety Strip HT and AZ 300T photo resist strippers also can be used to debond our adhesives.  You can get further information on these products at the links below.

 

Brulin's Safety Strip HT:  http://www.brulin.com/productdetails.aspx?pid=142&cid=44   

 

AZ 300T(Electronic Materials):  http://imicromaterials.com/products/photoresist-removers

 

Protective goggles and gloves should be used when handling chemicals.

 

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