Some prefinished, engineered (laminated wood) floors require a slightly different procedure for screening and coating than traditional solid wood floors. Answer the following questions prior to initiating a prefinished recoat job and you should be successful in the recoat of an old floor or overcoat of a newly installed floor.
Is the coating wrapped around the edge of the board?
If the prefinished coating covers the edges, then the water based finish being applied will not soak into the edges of the board. If the edges are uncoated and you are applying water based finish using the standard "squeegee" method, a significant amount of water may be absorbed into the sides of the boards, causing the floor to swell. As the finish dries, edges will appear raised.
To prevent this problem, coat this floor with a paint pad used out of a paint tray. Do not carry a puddle across the cracks. Apply enough finish to create a good wet coat. Seal the floor without putting a significant amount of finish in the cracks. When the first coat is dry, subsequent coats may be applied using the "squeegee" method. The edges of the floor have been sealed, so additional coats will not result in a problem.
Is there any "over-wood" between the boards?
Screen prior to any finish application using a 120 grit screen or finer. 180-240 grit sandpaper strips may also be used with a maroon pad, but be sure the screening process is thorough. Do not use a pad without sandpaper strips. The entire surface of the floor must be abraded uniformly. The screen or pad/strip will buff over the raised edge of the over-wood and skip the lowered portion of the next board and the finish can peel at those untouched edges. You must abrade those areas by hand if they cannot be reached by the machine.
Is this a "high wear" or standard UV coating?
NewAge products will bond to most "normal" UV coatings if properly prepared. There are a few "high wear" systems that contain anti-mar and scuff-resistance agents that prevent bonding even if well screened. If the manufacturers information does not contain information that specifically recommends (this means they have tested the combination and were successful), run the adhesion test yourself. A test patch is always recommended.
Has the glue been cleaned from the surface of a new installation? If so, with what?
Many glues are soluble only in certain solvents. Some of these are slow drying and leave a residue on the surface of the board that does not screen easily. Use a detergent wipe followed by a wipe with Maintenance Cleaner to make sure all solvent/glue residue is removed before abrading the floor. Good cleaning is recommended prior to any recoating job.
Was the bottom of the board below the tongue square edged or relieved (tapered)?
Water based finish trapped in the cracks tends to swell the board edges more if the flooring is square edged as opposed to tapered or relieved. A square edged floor should be treated as if there is no coating on the edges. Apply the first coat of water based finish with a paint pad.
Is the prefinished flooring coated with a clean UV coating or was it waxed or treated at the factory?
Waxing is not very popular now, but early UV's and some other types of prefinished flooring were treated at the factory so they could be stacked in boxes quickly without sticking together. These treatments can later cause adhesion failure when the floor is recoated. Ask the supplier about your wood. If unsure about any processes used, coat a test patch before coating the entire floor.
How has the homeowner been maintaining the floor? What types of products have been used on this floor?
In order for the finish to bond, all surface contaminants must be removed, and a clean dry abrasion scratch must be available for the coating to bond.
Waxes must be stripped, dust mop treatments must be removed, furniture polishes must be cleaned of the surface, and the floor must be clean and free of any soap residues BEFORE trying to screen the surface. Screening will not remove these contaminants but will instead only move them around.