Exterior Photopolymer Processing Guidelines

Exterior Photopolymer Processing Guidelines – When fabricating Novacryl photopolymer exterior signage, use only factory approved equipment manufactured by Nova Polymers in the US. Observe ALL Processing Guidelines for Peak Performance and to ensure ADA Compliance. Contact us at technicalsupport@novapolymers.com with any processing questions.


*Recommended Processing Time*
Main Exposure With proper vacuum and UV lamps@360nm * (Stouffer Scale reading of 12-13) 2:00 – 3:00 Minutes
Washout Tap Water at room temperature (90-95F) ** 4:00 Minutes
Dry Preheat dryer to 52C (125F) 20:00 Minutes
Post Exposure With no vacuum and UV lamps at 360mns 5:00 Minutes
Processing Note:*Exposure time may vary depending on the ages and strength of UV lamps. **Washout – Use FOUR to SIX ounces of XP Cleaner in the washout tank to aid washout. If copy areas remain Un-washed after processing time expires, you may use a fine bristle brush to clean in and around the copy. This should take no longer than a minute or two; otherwise, you may have an exposure problem unrelated to washout. Refer to SDS for the recommended concentration of photopolymer effluent for disposal. Consult local authorities for regulations in your area. Please consult Nova Technical Support if any of the above processing times fail to produce satisfactory results.


To improve the finish, clean with a fine wire brush with denatured alcohol, acetone or XP Cleaner prior to painting.

Processing Requirements: Be certain to rinse the washout tank with fresh water and fill to just below brush tips. Apply XP Cleaner in a circular motion atop the brushes. Change washout water after FIVE to EIGHT full sheets. When finished, drain the tank, rinse and fill with fresh water. Processing can be affected by the use of different photopolymer processing units, quality of film and age of UV lamps. The photopolymer layer of NovEx is VERY soft prior to initial exposure. Handle and cut with care. Advanced processing techniques can eliminate handling difficulties.

Advanced Processing Techniques

CLEANING EXCESS RESIDUE AFTER WASHOUT: If excess residue is present on the adhesive layer, place the NovEx sheet in the water basin or screen wash rack and brush with a 50/50 solution of XP Cleaner and water. This will remove excess residue from the adhesive layer. The material is thoroughly cleaned of residue when you see water “bead” off the material as if it were waxed.

IF EXCESS POLYMER APPEARS BETWEEN OR WITHIN CHARACTERS: Due to its high content of synthetic rubber and the fine thickness of many photopolymer washout unit brush systems, it is possible that all photopolymer may not be washed away from between enclosed characters such as “A” and “B”. In general, this unexposed polymer has absorbed sufficient water and is ready to be washed away. Use
a nylon brush dipped in a 50/50 solution of XP Cleaner and water, use a screen wash basin and pressure wash the characters if needed. The excess polymer will be immediately removed.

IF MATERIAL APPEARS “OVEREXPOSED”: There are reflective characteristics within the photopolymer resin of NovEx. This may cause minor “fill” of certain bold fonts. The fill-in will show up in characters such as “M”, “A”, “N”, and “W” where the angles are sharp and light penetration is excessive. To eliminate this, simply cut back the main exposure time to 1:30. If you run a smaller Braille diameter, a
double exposure may be necessary to achieve proper shoulder draft. To do this, expose the plate as normal, then pull out the exposure frame without turning off the vacuum, and place Rubylith strips over the characters, leaving the Braille exposed. Push the exposure drawer back in and expose for another 1:30–2:00 minutes.

OTHER TIPS TO OPTIMIZE YOUR PRODUCTION TIME AND OUTPUT: If aluminum does not stick to your green mat for washout, wipe both the green mat and the back of the aluminum plate (after exposure only) with isopropyl alcohol. If you do not wish to use your washout tank for washout, or do not find it efficient, you may place exposed plates in a developing tray, or water basin, filled with warm water
and a few ounces of XP Cleaner. Allow soaking for 15 minutes. Remove from tray and power wash the plates using warm water in your screen wash basin. Blow off excess water, dry and post expose as usual.

Advanced Processing Data to minimize handling errors, we recommend the following processing sequence for NovEx: Apply a high bond, exterior grade adhesive (MacBond or similar) to pre-cut cast acrylic in the desired thickness. The acrylic should be in a sufficient quantity for all exterior photopolymer sheets in the job. Oversize cuts should be no larger than 19” x 25” and quantity should
be determined in advance. Once the adhesive is applied, stack the acrylic near the photopolymer unit and begin processing. Immediately after the EXPOSURE phase, remove the NovEx sheet from the processor and LAMINATE to the cast acrylic. You may use the adhesive liner to cover the polymer layer while laminating. Use a rubber brayer or laminator and press aggressively. The exposed material will
not be harmed no matter how hard you press. Return the laminated NovEx to the processor and resume processing as normal (washout, dry, post). (Note: The material now handles like solid based Novacryl. Water does not migrate into laminating adhesive).

Technical Data and Downloads

21 Step Stouffer Scale Video

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