Delaminating Finishes on Laminate Floors
The finish separates from the wood flooring or from existing layers of finish. The finish peels away in sheets or strips.
Delamination of finished can be caused by a variety of non-related causes. It is usually caused by one rather than a combination of these causes.
- Surface contaminant causing barrier to good adhesion, such as oil, wax, oil-based soaps, other cleaning products.
- Sanding dust left from improper cleaning between coats.
- Using finishes that are not compatible.
- Excessively fine sanding finish of bare wood prior to application of finish.
- Over coating finishes that are not yet dry.
- Skipping abrasion between coats.
Some surface contaminants such as oils or waxes from previous finishes, or body fat associated with sports floor use may not be completely removed by sanding. It is believed that heat generated during sanding causes expansion of oils and leads to a reduction in the viscosity (thinning) of the contaminant which enables the contaminant to further penetrate the wood fibres. See solutions.
- Was the floor previously finished with oil or wax finish, before recoating?
- Is the finish delaminating from the bare wood, or from previous coats of finish?
- Is the finish over coated onto another finish? If so what type?
- Was there any screening, sanding or abrasion of any sort between coats?
- To what grade was the floor sanded prior to finishing?
- Was the fine finishing dust removed from the floor surface before application, if so how?
- Were the components of the finish properly mixed (where applicable)?
- Was there any delay in the drying of the finish?
First establish if the finish is delaminating from the bare wood or from previous coats of finish. Check for signs of abrasion that may indicate that unreasonable wear may be contributing to the problem. Occasionally surface contaminants such as oil can be seen or felt on the bare wood surface or between coats of finish. Adhesion of coatings including wood finishes can be tested with a pull off adhesion tester conforming to ISO 4624, ASTM D4541
In many case where finishes have delaminated it is necessary to re-sand and seal the whole floor. Where the defect is limited to a small area, localised sanding and refinishing can produce satisfactory results.
Where finish is delaminating due to suspected surface contaminant such as oil or wax, the floor can be thoroughly re-sanded, a primer barrier seal can be used to create a barrier before application of the surface finish to aid adhesion.
Where body fat is suspected (on sports floors etc.) to be the cause of poor adhesion, following re-sanding, the wood surface can be cleaned using a washer-scrubber-dryer and purpose made body fat neutraliser, before application of a new finish.
When using ethanol based primers, be aware that these can cause edge bonding which can lead to rafting. As such these are less well suited to large floors, and where there will remain gaps between boards at time of finishing. Furthermore the rapid drying of ethanol based primer barrier seals make them less well suited to large floor areas, as this can lead to overlap streaks.
An alternative to using a lacquered finish is to use an oil or wax finish which are less likely to be affected by oil based surface contaminants.
Other steps to solve / avoid delamination of finish include:
- Courser final sanding (e.g. 80 grit) especially on some dense timbers can improve adhesion.
- Thorough removal of sanding dust from wood surface.
- Use of a barrier seal primer where appropriate (oil, wax contaminated floors).
- Appropriate choice of finish for compatibility, additive to promote adhesion available for some products.
- Proper mixing of finish components.
- Allow appropriate drying time between coats.
- Abrasion between coats.
- Tacking between coats.
- Ensure appropriate curing time before resuming normal use of floor.
- Consider using an oil finish as an alternative to lacquer in cases of petroleum based contaminated floors.
Whatever method of remedial action is used, always try a suitable test area before commencement.