Why Enamels Can Dry Slowly

By Jim Hingst 
@hingst_jim 

Oil based enamels do not dry through evaporation. Instead, curing occurs as the paint reacts with oxygen, resulting in polymerization. This reaction with oxygen can actually continue for years during which the physical properties of paint can change. Reactions between different coats of primer and paint can also complicate drying.

Sign enamels are usually dry to the touch after 6 hours and ready to handle after a day. If your paint is drying too slowly, here are a few possible causes:

1. The chemistry of today’s paints is complex. In the past, you could get away with using any number of different solvents to thin paint. Modern paint formulations are not so forgiving. Always use the reducers recommended by the manufacturer.

2. The environment plays a big role in drying time. Oil paints, by their very nature, take longer to dry than water based paints. Drying can take longer when ambient temperatures are lower or when humidity is higher. If you are painting with 1-Shot lettering enamel, use their #6001 Low Temp Reducer, when the temperature is below 65° F.

3. Application also affects drying. Make sure that the paint is thoroughly mixed before application. Prior to paint, prep the surface to remove any contaminants, such as wax or grease. Prime the surface with a primer recommended by the manufacturer to ensure compatibility of materials.

4. Do not thin the paint any more than is required to achieve the desired viscosity for brushing. Apply thin coating of paint.

5. Allow sufficient drying time between coats of paint. When shop conditions are optimal, you still should allow at least 12 to 16 hours between coats of paint. Sometimes more drying time between coats is needed, especially when the ambient temperature is between 50° F and 65° F.  At temperatures below 50° F the paint may not dry completely. 

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About Jim Hingst: After fourteen years as Business Development Manager at RTape, Jim Hingst retired. He was involved in many facets of the company’s business, including marketing, sales, product development and technical service.

Hingst began his career 42 years ago in the graphic arts field creating and producing advertising and promotional materials for a large test equipment manufacturer.  Working for offset printers, large format screen printers, vinyl film manufacturers, and application tape companies, his experience included estimating, production planning, purchasing and production art, as well as sales and marketing. In his capacity as a salesman, Hingst was recognized with numerous sales achievement awards.

Drawing on his experience in production and as graphics installation subcontractor, Hingst provided the industry with practical advice, publishing more than 150 articles for  publications, such as  Signs Canada, SignCraft,  Signs of the Times, Screen Printing, Sign and Digital Graphics and  Sign Builder Illustrated. He also posted more than 450 stories on his blog (hingstssignpost.blogspot.com). In 2007 Hingst’s book, Vinyl Sign Techniques, was published.  Vinyl Sign Techniques is available at sign supply distributors and at Amazon. 

Slides of Jim's Artwork

© 2017 Jim Hingst