Tips From The Experts
Consider pedestrian safety as a factor in sealer applications
One of our good customers, a pavement contractor, called with a question from one of his municipal clients. The city had a project to reseal a public walkway but also had a mandate to use environmentally friendly processes and products on the project. Both the city and the contractor were worried that most commercial sealers contained solvents which would not qualify as "green products". Our techs had the answer for the customer but they raised the additional question regarding the non-slip, tactile nature of the pedestrian way after a sealer was applied.
SurfaceLogix manufactures and sells two products, Cobble Coat H2O and Cobble Loc, which are low VOC and eco-friendly. Both are water-based products and produce a hard, UV resistant coating. However, since the products are film-forming coatings, they can at times be slippery, particularly after a rain. So the SurfaceLogix techs wanted to solve two problems at once: both the requirement to be "green" and the tactile, "gripping" nature of the hardscape surface. They recommended #139 Impregnating Sealer, which leaves the surface of the walkway unchanged but protects the substrate from oil, grease, spills, or other liquids. The #139 Impregnating Sealer penetrates the substrate to protect and preserve the walkway but does not leave a film on the surface.
Consequently, the municipality, overrode the original specifications for a film-forming coating and chose a low VOC, water-based impregnator that met all of their objectives. The contractor was also pleased because he could pressure clean the walkway and seal it the same day with a single coat, therefore saving him labor and travel expense.
Always follow the manufacturer's instructions
Recoat times are specifically printed on the label to get the best results from the product. For instance, with SurfaceLogix' Cobble Coat you can walk on the first coat within one hour, however the recoat time is four hours. The additional drying time allows all of the entrapped solvents and drying agents to be released. If you apply a second coat too soon, the solvent from the second coat can absorb into the substrate with little "holdout," therefore requiring more material to create the same look.
What to do when faced with an unknown floor coating
You have to be a detective when it comes to going over an unknown floor coating
The easiest and first question to ask is whether an old can is available to determine if the coating is solvent or water based. It is generally best to recoat with similar chemistry. For example, apply a xylene-based stain over a xylene-based stain.
An old xylene-based sealer can be determined on the substrate simply by rubbing xylene into the film in a small circle. The coating will re-emulsify in less than 10 seconds and turn back into its liquid state if it is xylene-based. A water-based sealer will tend to fight the xylene and may become gummy.
Test patch - It is always recommended to apply a test patch of the material that you have determined is most compatible with the old film. A test patch area or areas of the preferred coating is put down over a clean and dry surface. Let it dry for 24 hours. Take a straight razor blade and cut a tick-tack-toe pattern pressing hard through both coatings. Place a piece of duct tape and press over the cuts. Rip it off. If the tape doesn't pull up the coating between the tic-tac-toe cuts, then you have good adhesion. The final suitability of the surface is the responsibility of the applicator.
Preparing previously coated concrete surfaces
Coloron Concrete Sealer is ideally suited for coating bare concrete surfaces by following the steps on the label. When coating a previously coated surface several things should be determined. First, ensure there is complete compatibility between existing Coloron coat and the new coat. When the new coat is added it will result in solvent weld, forming one film that is inseparable. However, if another coating is present, its compatibility must first be determined before recoating. Normally if the existing coating will reliquify from contact with xylene, then compatibility is most probable. If the old coating resists the xylene and remains intact, then sandblasting or stripping is recommended. The final suitability of the surface is the responsibility of the applicator.