USEPA RULE AFFECTING PAVEMENT MARKING PAINTS By WILLIAM T. SUNLEY, Engineer of Local Roads and Streets Credits to: Lee Bates, Policy & Procedure Engineer.

The United States Environmental Protection Agency has proposed restricting the manufacturing of pavement marking paints containing more than 150 grams per liter of volatile organic compounds (VOC) effective April 1, 1997. This would affect IDOT and local agencies by requiring that they use pavement marking materials other than solvent-borne paints.

There are a number of alternate pavement marking materials that may be used, including epoxy, thermoplastic. However, the most widely used substitute for the solvent-borne paints will probably be those paints that use water as a carrier known as water-borne paints.

Pavement marking equipment designed for placing solvent-borne paints is usually not acceptable for placing water-borne paints. The tanks and fittings must be stainless steel or coated with epoxy or other non-reactive material. Gear pumps must be placed with diaphragm pumps since gear pumps shear the paint, which degrades the quality of the water-borne paint.

IDOT has already started applying water-borne paint for pavement markings. Several years ago they purchased 23 new paint stripers with stainless steel tanks, however it was still necessary to install stainless steel fittings and replace the pumps in these units.

Water-borne paints dry in a relatively short period of time but are more sensitive to pavement moisture content and low pavement temperatures than solvent-borne paint. However, workers like to use water-borne paint because of the lack of fumes.

IDOT developed its own specifications for water-borne paint. Local agencies may purchase water-borne paint under the current state purchase contract. While IDOT is satisfied with the product they may make further changes in its formulation.

Silicone coated beads (Type B) must be used with water-borne paint since they float on the surface of the paint until it hardens. Untreated (Type A) beads are used with solvent-borne paints since they bond better than the silicone coated beads.

A low VOC solvent-borne paint is being developed by Centerline Industries, a Missouri based paint manufacturer, using acetone as the solvent. The Missouri Department of Transportation is testing this paint and IDOT plans to evaluate it later this year. This paint can be used in paint stripers that have not been converted for water-borne paints. One problem with the acetone solvent paint is its low flash point.

Local agencies have several options for pavement markings. They may choose to convert or purchase new equipment that will apply water-borne paint or hire a private contractor to apply this paint. They may also choose one of the alternate materials previously mentioned or use paint with acetone solvent if this product proves to be satisfactory.

There may be another option. The federal rule for VOC paints may allow users of these paints to pay a penalty for continuing their use, possibly in the form of surcharge added to the price of the paint. The extent of the penalty has not yet been finalized. While this may result in expensive paint, the user of the small quantities of this paint for traffic pavement markings may find this more economical than converting or purchasing new equipment.

Local agencies should be aware that with the small amount of solvent-borne paint on the market, even small quantities may be hard to locate and purchase. •

October 1996 / Illinois Municipal Review / Page 13