Painting Novacryl

All photopolymer signs require a topcoat to be applied.

painting novacryl photopolymer signs

Painting Novacryl – Many photopolymer signs are surface painted using a variety of custom colors. Signs that are decorated subsurface with paint, digital graphics and materials that incorporate color or patterns in the base substrate all require a clear coat to apply over the photopolymer. This adds the same level of protection as the paint and should be applied accordingly.

According to Matthews Paint Company, it is specified that clear coats and/or paints should have the same amount of coating (4 mil wet/2mil dry).

It should be noted that when using clear coats, the product chosen needs to have a high level of UV protection, needs to be mixed properly and be applied to the manufacturer’s recommendations.

WATCH THE VIDEO and learn how to paint Novacryl photopolymer using Matthews Paint.

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Click here for Painting/Top Coat FAQ

Recommended Novacryl Painting Procedures

Recommended painting procedures for Novacryl photopolymers

When coating Novacryl or Nova Polymers, with MATTHEWS ACRYLIC POLYURETHANE, the first step is to clean the polymer. It must be free of any dirt, grease, etc… You may use any of our reducers or isopropyl alcohol

When using MATTHEWS ACRYLIC POLYURETHANE, make sure the surface is clean. Apply one coat of 74-777 TIE BOND and allow to tack up approximately 20 minutes at 70 degrees Fahrenheit. Then topcoat with MAP. It is NOT necessary to use TIE BOND for good adhesion.

When using VOC compliant MAP, our compliant coating for air regulations, be sure the photopolymer is clean. Then apply our VOC compliant material directly to the PHOTOPOLYMER. No TIE BOND is necessary for good adhesion.

Top coating of MAP and VOC MAP should be done within 72 HOURS. After 72 HOURS. After 72 hours a light scuff sanding with 400 grit sandpaper is required for good adhesion of any top coating.

Complete Matthews Paint Company Substrate Guide

Substrate Preparation Recommendations

Step #1 – Matthews is for Professional Use Only.

Step #2 – Always follow proper safety precautions when using Matthews’s products.
Safe usage requires reading, understanding, and following all label, SDS, and other product literature before use.

Step #3 – The spray area and substrate must be warm and have adequate airflow.
Application of primers, topcoats, and clear coats should never take place in temperatures under 60F/16C. Substrates should also be brought to or above this temperature guideline before applying any primer or topcoat.

Step #4 – Properly clean the substrate.
Professionals don’t even think about priming or painting over any substrate that hasn’t been properly cleaned and prepared. Use proper cleaning products and procedures.

Step #5 – Use the right primer for every specific substrate.
Always use the appropriate primer and application techniques suggested from Matthews substrate guide.

Step #6 – “When in doubt, test it out.”
Recommend testing first, the process for any new product, primer, or first-time application procedures before permanent production begins. Remember that the change of seasons affect the temperature and humidity during application so periodic testing on application and adhesion confirms the product and production performance.

Step #7 – Choose the proper reducer for each application.
Review product data sheet for reducer temperature guidance.

Step #8 – Allow specific time between coats.
For both primers, topcoats, and clears, extend flash times between each coat application.

Step #9 – Adjust spray equipment.
Perform a spray pattern check prior to painting. Adjust flow, pressure, and tip if necessary. Use in well-ventilated facilities and with proper safety equipment.

Step #10 – Contact Matthews Paint Company with any questions.
Matthews’s customer service and technical assistance are both available for any color formula match, specification, or technical question that may arise.

For more complete information on all MPC solutions, you can click here

How to Clean the Polymer Sheet Before Painting


When applying paint to sub or 2nd surface clear Novacryl, you must clearcoat the first surface to protect the photopolymer. Follow cleaning procedures.

  • Clean with 6428SP Plastic Prep or 6405SP Low VOC Cleaner.
  • Can use 6428SP Plastic Prep as an anti-static agent by applying a mist coat and allowing to dry.

Topcoat Direct:

  • Apply 1 medium wet topcoat.
  • Allow 10-15 minutes to flash.
  • Apply 2nd medium wet topcoat.

Learn more on Matthew’s website

Matthews Trouble Shooting Guide

Wet film thickness (WFT) gauge

How do I use a wet film thickness (WFT) gauge?

A wet film thickness gauge is designed to give the spray operator immediate feedback as to the film builds just sprayed. In most cases, measuring the dry film thickness (DFT) provides little information as it is usually measured a considerable amount of time after the actual spraying. Many things could have influenced the DFT: operator fatigue, ambient air temperature, coating temperature, etc.

There are several types of WFT gauges available. The most common being the notch gauge (see figure 1). Other types including the eccentric disk, the rolling notch gauge, and the 6 sided gauges are available from specialty vendors.
Figure 1 – There are several issues that must be addressed when using a WFT gauge.

  1. Technique
  2. Timing
  3. Reading with clear coats
  4. Creating surface defects

Technique
When placing the gauge on a freshly painted part, the gauge must be placed 90 degrees to the part. The operator also needs to be aware of the variation of the surface that may influence the reading. For example, if the surface is not perfectly flat, one direction may give a more accurate reading than another.

To use the WFT gauge, place the gauge directly on the wet finished part (see figure 2) and as described above. The notches will indicate the measured film thickness. For example, if the 1 and 2 mil notches are wet and the 3 and 4 notches are dry, then the measured thickness is between 2 and 3 mils (.002 to .003 inches).

Figure 2 – Timing
The solvent in a coating will immediately start to evaporate after spraying. In order to achieve a common method of reading the coating thickness, a time frame will need to be established. Typically, one might measure the thickness of 5 to 10 seconds after spraying. If another operator measures the thickness after 20 seconds, the results would be different even if the initial thickness was identical.
Reading with Clear Coats
A clear coating on a WFT gauge would be very difficult to read. The most common method of reading clear coats is to use the gauge as a stamp on a piece of absorbent (non-gloss) paper. Many companies use the stamp method as a way of documenting the WFT.
Creating Surface Defects
After using a WFT gauge to check the film thickness, the material may not flow to hide the area where the gauge was used. If this creates an undesirable defect, place a small sample of the material in line with the operator’s normal spray path. This sample should be sprayed along with the part. The sample then may be checked for WFT and DFT (after curing).

How to Clean Novacryl After Painting

Cleaning a Painted or Clear Coated Novacryl

Download the Matthews Cleaning Guide

  1. The maintenance and care of a painted or clear coated polyurethane surface would utilize the basic commercially available non-abrasive cleaners and polishes recommended for finishes exposed to the environment.
  2. It is recommended to wait at least 30 days after painting before any cleaning or polishing is attempted.
  3. A mild detergent and water solution with soft cloth toweling is often sufficient to remove most dirt followed with a thoroughly clean water rinse.
  4. Application of polish (liquid or paste) should be done with a wet soft cloth-covered sponge and buffed with a soft flannel cloth. This is best accomplished in the cooler hours of the day avoiding direct sunlight, if possible.
  5. Use of polish over satin finishes may result in an increase to the gloss level.
  6. Any questions should be directed to the manufacturer’s recommendations.

Matthews Paint Substrate Preparation Guide

Photopolymer
Nova (Novacryl PT and Novacryl EX)

! Use proper Personal Protective Equipment (PPE) during product application.
! 6405SP/01 or 6410SP/01 can be used as cleaners in VOC regulated areas but will not provide the same anti-static properties of the non-compliant 6428SP/01 Plastic Prep.

First Surface Painting (Tie Bond not needed):
  • Clean with 6428SP/01 Plastic Prep, 6405SP/01 Low VOC Cleaner, or 6410SP/01 Low VOC PreCleaner using a short-bristled brush.
  • While surface is still wet, blow dry with compressed air.
  • Apply a mist coat of 6428SP/01 Plastic Prep and allow to dry in order to reduce static surface charge.
  • Topcoat or Clearcoat directly per technical data sheet recommendations.
Optional Second Surface Painting of Novacryl PT (Tie Bond not needed):
  • Clean with 6428SP/01 Plastic Prep, 6405SP/01 Low VOC Cleaner, or 6410SP/01 Low VOC PreCleaner using a short-bristled brush.
  • While surface is still wet, blow dry with compressed air.
  • Apply a mist coat of 6428SP/01 Plastic Prep and allow to dry in order to reduce static surface charge.
  • Topcoat second surface directly per technical data sheet recommendations.
  • Important! When applying paint to second surface Novacryl PT, you must clearcoat the first surface to protect the photopolymer. Apply clearcoat per technical data sheet recommendations.

Photopolymer
Nova (Novacryl LP, Novacryl ECR-3, Novacryl AL and Permaglow)

! Use proper Personal Protective Equipment (PPE) during product application.
! 6405SP/01 or 6410SP/01 can be used as cleaners in VOC regulated areas but will not provide the same anti-static properties of the non-compliant 6428SP/01 Plastic Prep.

First Surface Coating:
  • Clean with 6428SP/01 Plastic Prep, 6405SP/01 Low VOC Cleaner, or 6410SP/01 Low VOC PreCleaner using a short-bristled brush.
  • While surface is still wet, blow dry with compressed air.
  • Apply a mist coat of 6428SP Plastic Prep and allow to dry in order to reduce static surface charge.
  • Clearcoat directly per technical data sheet recommendations.

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