MPC Quick Tip: Expert Advice On Demand!

Frequently Asked Questions

Q. What is the coldest temp I can spray Matthews sign paint at?

A. Inside and outside: 60-65 degrees minimum. Substrate and paint should also be at these minimum temperatures.

Q. What will happen if I do spray below 55 degrees?

A. Product won't crosslink.

Q. Do I need a respirator?

A. Yes! Yes! Yes! Supplied Air is recommended for everything.

Q. What Matthews primers can I put on top of Matthews sign paint?

A. Epoxy primers, U-Prime, No wash primers or Polyester Primer

Q. Can you put MAP over screen print coatings?

A. Most silk screen materials are enamels, and Matthews may lift enamels. Epoxy and urethane screen prints can be topcoated or cleared with Matthews.

Q. Can you put MAP over sign foam?

A. SignFoam—Yes, with Polyester Primer, U-Prime or Epoxy. Styrofoam—No, it will dissolve foam.

Q. Can you apply Matthews over existing coatings?

A. In many cases you can, but each instance should be tested first.

Q. What primer is recommended for wood?

A. Results may vary since there are many kinds of wood and wood products. Basically wood needs to be moisture-free. Wood MUST be dried or kiln-dried to avoid blistering. The best primer would be epoxy. As always, testing is recommended prior to application.

Q. Can concrete be painted with Matthews Paint?

A. The porosity of the concrete will determine number of coats of epoxy to apply. Concrete should be properly cleaned to remove form release agents. Muriatic acid is best choice for cleaning / etching. Testing is always recommended.

Q. How can I get the sign paint to dry faster?

A. Bake it, use accelerator, increase air flow, and/or add reducer to assist flash. Use proper mix ratios and spray techniques.

Q. What are recommendations when sign paint dries too fast?

A. If due to environment—use slower solvent and/or catalyst. Otherwise apply wetter, thicker film build.

Q. Paint dries too fast, even with 6396SP Slow Reducer?

A. Add 45-251SP retarder to reducer mix. Use 43-999 slow catalyst in place of universal catalyst (43-270SP).

Q. What causes sign paint to bubble, alligator, blister or lift?

A. •  Incompatible substrate or undercoat
•  Improper catalyzation or improper use of accelerators
•  Topcoated outside cure window
•  Overbaked or baked without purge/flash time

Q. How long after I paint can I wrap and ship?

A. Depends on sign size, composition/construction, and ambient conditions. Best to determine your own window onsite.

Q. What is the difference between dry and cure times?

A. Dry means out of dust. Cure means through dry.

Q. What happens if I do not put in the proper catalyst?

A. Crosslinking doesn't occur or occurs partially. Poor performance will result, lack of long term durability.

Q. How many coats do I need?

A. Normally two coats, regardless of number of passes. Minimum 2 mil dry film for topcoats.

Q. The sign paint doesn't seem to be hiding, what do I do?

A. Use hiding stickers to help determine number of coats, obviously add coats, add stronger basecoat color to get hiding first then topcoat with weaker color, and make sure that paint is not over-reduced.

Q. What are recoat windows and recoat problems?

A. Recoat problems occur when trying to apply additional sign paint to a freshly painted surface (to repair a defect or for other reasons) when the original paint film is in its crosslink window.That window is an amount of time in which the paint film is still very fresh but not wet, yet not dry enough to resist the solvent from additional coats of paint. Typically a paint film will lift or wrinkle if additional coats are applied during this window.
Actual recoat times vary according to film build, technique, application and individual product.
Basically speaking, try to apply all of the coats of sign paint you intend to spray at one time following recommended flash times. If additional coats are necessary later to repair a defect, wait until the paint has dried overnight or force dry it for a comparable time.

Q. How do I get rid of the white spots when I use flattening paste?

A. Stir, shake, and strain. Verify proper order of addition of ingredients.