Crosswalks, stop bars, turn arrows, and lettering ("ONLYs") increasingly have become targets for the more-expensive but longer-lasting thermoplastic markings, so many contractors are considering adding this service to their pavement marking operations.
Thermoplastic, as applied to pavement, is a molten material created from melting either plastic granules or a pre-mixed material that is heated, cooled, and formed into a block which is then melted. Material is heated to 400°F - 425°F before it is applied to the pavement by a walk-behind thermoplastic handliner.
Handliners are smaller, portable pieces of equipment that hold the molten material and maintain it at the proper temperature long enough to let the operator apply it to the pavement. Made of either steel or aluminum, handliners are pushed by the operator - none are self propelled.
Each handliner features a tank to hold the molten plastic, a manual agitator to enable the operator to keep the material mixed, and a propane-fueled burner beneath the holding tank and on the side of it that heats the die that accept the molten material from the tank and form it into shape on the pavement.
Manufacturers agree that the most effective way to heat the material is in a kettle - separate pieces of equipment attached to a stake truck or trailer. Heated by either diesel or propane, the kettles are designed to heat the granules or blocks in large amounts and to maintain the material at a specific temperature while the crew is placing markings. The operator pushes the handliner to the trailer, gravity flow fills the handliner tank with the molten material from the kettle, and the operator returns to marking the pavement.
Manufacturers acknowledge that handliners can be used to melt the material, but while that approach costs significantly less initially than buying additional kettles, it is inefficient. It will take at least 60 minutes to heat material from granules or block in a handliner. Once the handliner is empty it will take a minimum 45 minutes to heat enough material to get back to work.
"It's a slow and laborious process when done without pre-melter kettles," says Steve Shinners, vice president of sales and marketing, MRL Equipment Co. "If you're only heating and planning on putting down 500 or 600 pounds of material daily it can be done, but as soon as you get to a level where volume is an issue and productivity is an issue you need to consider buying kettles."
Shinners says the majority of handliners MRL sells are sold in some type of a package with pre-melter kettles. "It's really all about melting. How much you can melt and how fast you can melt it dictates how much you can put down in a typical shift," Shinners says. "It's really foolish to think you are going to be in this business and try to compete by heating the material in the handliner itself."
Tom Waxler, president of Advanced Striping Equipment, agrees. "If you're looking to save money and improve efficiency, buy a kettle and the granular form of plastic. It will save you money and improve your efficiency," Waxler says.
Advanced Striping Equipment,M-B Companies, and MRL bridge these two approaches by offering a pre-melter option for their handliners. These pre-melters attach to the handliner tank, and unmelted material can be added to the pre-melter as the operator is working. As it melts, the molten thermoplastic flows into the holding tank from the pre-melter unit. A screen between the holding tank and the pre-melter prevents unmelted material from flowing into the tank, where it could cause a block from the tank to the die.
"That's the only way we recommend melting material in the handliner," says Marvin Mayle, technical services, M-B Companies. "Any other way is not cost effective because it just takes too long."
Ease of operation
Because handliners are push units, manufacturers suggest testing them out if you can before buying. "These machines carry a lot of weight so if you've got an operator pushing one you want to be sure it moves as resistance-free as possible," Waxler says.