Touching up waterborne finishes
Things to consider when repairing waterborne topcoats. 1998.
by Rick Hill
How easy is it to touch up or spot repair a damage or defect on a waterborne coating? Will the repair blend in? What coating or materials would you use to do the touch up? How easy is it to strip these finishes? Do they gum up when you use a chemical remover on them?
Waterbases can be very hard depending on the manufacturer. They can be touched up and stripped in a similar process to a precoat or catalyzed lacquer. This means that the water base coating when cured will not allow the next layer of coating to dissolve into it (a chemical bond). In most industrial water bases the coating is tougher when cured than the solvents in it. So, to get the second coat to adhere to the first coat you must create a mechanical bond between them. This is done by scuff sanding the original coat lightly, thereby creating grooves in the finish that the second coat can grip onto.
There are a plethora of classes, kits, and franchises that focus on the touch up industry. I usually direct my customers to either Star Finishing or Mohawk for these products. They have made a science of the touch up business and have a product for every type of scratch and nick in the wood industry. Ask any local refinisher for his contact at one of these companies. Though the products may vary based on the coating, the process is no different for waters than it is for other coatings.
As to stripping, it will depend again on how tough the water base is. We have a two component water base that will need methelyne chloride if we ever have to get it off. Whereas the common water base floor coatings found in retail stores can be stripped with the type of chemicals found in products like 3M's safe stripper. Ask your supplier on their suggested stripper.
Rick Hill is an independent representative and consultant for industrial wood finishes. He has been involved in the woodworking industry for 12 years, and has been known to actually hold, shoot, and clean a spray gun.
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