photoresist film

Facts You Should Know About Photoresist Film

With over 35 years in the glass business, Ruth Dobbins offers experience in fused and cast glass, as well as in glass-etching techniques. Ruth holds a Master's Degree in Printmaking and Art History and has been a partner in a stained and fused glass wholesale supply company in Europe, which also placed great emphasis on a training program. For the past 20 years, she collaborated with her husband Norm Dobbins in commission work, writing books and creating videotapes on how-to techniques for glass etching. Ruth taught these techniques for 30 years in the U.S. and other countries. Ruth continues these venues by offering a complete training program at Aliento School in Santa Fe, New Mexico, and by teaching at various trade shows, including The Awards & Engraving Show. One-on-one training and consulting services are also offered. You can reach Ruth by email at, by phone at 505-473-9203 and by fax at 505-473-9218. Check out the website at

Common to all photoresist films are a couple of facts: you should work under yellow light/safe light conditions, and you need an exposure unit. For most of you that means the use of a small unit commonly referred to as the Letralite.

The exposure light uses an ultraviolet light tube to expose photoresist film to the artwork created. The lightbulb is surrounded by an acrylic cylinder that sits a few inches above the bulb, assuring equal distance to the light source no matter where you place your film. The cylinder is covered by a stretchy blank blanket that makes optimum contact possible between the artwork/film sandwich onto the cylinder in a specific way: first, the printed side of the artwork needs to face the emulsion side of the photoresist. Once you have that sequence correct, you need to make sure that the backside of the artwork faces the exposure light. If you reverse either of those two steps, you will not get an exposure. 

This is true for all photoresist films, no exceptions. Once you get to this point, you need to refer to the user guide of your specific photoresist to determine the exposure time. Make sure you pick the right exposure time for the thickness of film you are processing or again, you will not be successful.

—Ruth Dobbins, Your Professional Glass Consultant 

Read more about the importance of correct photoresist processing in the October ’18 issue of A&E