The two most common problems with sealer application are ‘lap lines’ and ‘roller marks’. The lap lines are caused by the ‘push-pull’ applicators and roller marks are caused obviously by ‘rollers’. Rollers are used for lower-viscosity concrete sealers while push-pull applicators are used for higher-viscosity sealers or coatings. The roller marks or lap lines can show up with any sealer or coating and on any surface or substrate. These are created by physical forces exerted on the liquid sealer during application.
How to avoid them –
a. Do not overwork the roller – If you over work the roller, the roller lines are bound show up. A light touch and light thin coats are the best approach.
Spray application is the best, as it eliminates the ‘overworking’ aspect and pretty much guarantees a uniform application without roller marks.
b. Do not overload the roller – Overloading the roller with the material will cause roller marks and if using a push-pull applicator, pour the sealer directly onto the substrate and push and pull until a thin film has been achieved.
c. Porosity of the surface – If the surface that is being sealed is porous, it is best to spray the sealer. A roller or push-pull applicator is bound to leave a roller line or lap mark.
d. Maintain wet edge – Each subsequent pass of a roller or applicator should cover 2 or 3 inches in the previous pass. This assures that any sealer build up on the previous edge is knocked down, eliminating a lap line.
Using the right applicator and good application control are keys to eliminating roller marks or lap lines for future sealer projects. A light touch slow and easy on the roller or applicator, and not overworking the sealer or coating leaves a uniformly sealed surface.
Please watch the video clip showing the application of water based acrylic, epoxy and polyurethane sealers.