Recommendations for a flawless glossy finish

The high gloss of furniture, flooring, musical instruments and other such examples of finished wood is hard to achieve. It requires a lot of hard work and following certain rules. While with a matt finish, some faults can be overlooked and are invisible to the vast majority of those who look at it, with a gloss finish, the flaws are very visible. The gloss highlights all the flaws, making them visible even to the uninitiated.

It is not enough to use a good quality high-gloss varnish to achieve gloss. If certain requirements are not met in terms of working technology, product preparation methods and the conditions in the workspace, no matter how good the varnish is, it will not work wonders. That is why I am going to show you what, in my opinion, are the conditions that must be met in order to achieve a high quality gloss.

Perfectly flat surface, free of bumps and unevenness

The gloss of a finish expresses the extent to which a finished surface reflects light. In the case of high gloss the percentage reflecting light approaches 100%. For this, the surface should be as flat as possible, without any bumps or roughness. Obtaining this surface starts as early as the white sanding of the wood, which is done with sandpaper with successive grits, starting from 80-100 and going up to 180-240. There is no need to do sanding with each individual grit level. It is sufficient if 3 different grits are used (see also here). Also, sanding paper should be replaced after the recommended time of use or if it is heavily clogged.

The primer applied must be full-bodied, hard and in sufficient quantity to allow very good sanding. Sanding removes the roughness and orange peel appearance, providing a perfect surface for the gloss varnish. The most suitable primers are polyester, polyurethane or UV-curing primers (polyester, acrylic, polyacrylic, etc).

Do not sand the primer with a grit size less than 400. Because of the sheen, the fine grains created by sanding with finer grit paper will become very visible.

Thinner is very important

The varnish needs to have time to soak thoroughly before it starts to dry. This is why use a slower, good quality thinner, whatever the season. If it is not very well stretched and the surface has orange peelmust be made polishing. Polishing or buffing is a more advanced sanding process, which is carried out with very fine-grained abrasive materials up to 4000 grit.

Clean, dust-free space

The area where the varnish is applied and dried must be free from dust and airborne impurities. The varnish has a longer drying time and thus impurities can be more easily embedded in the film and become very visible due to the gloss. It is very difficult to get a proper gloss finish in a regular finishing room with a normal spray booth, without polishing. No matter how clean the working environment is there will always be impurities in the air. Pressurized spray booths or encapsulated and pressurized finishing lines can be used to reduce them as much as possible. Even so, impurities may still occur from time to time, which are also removed by polishing.

Good quality varnishes

The gloss varnish used must be of good quality, spread well and if it is a hardener varnish, it must not be fast. At the time of application it should be at approximately the same temperature as the wood substrate and the surrounding environment. The recommended temperature is between 18 and 20°C. Slight variations from this range are acceptable, but the greater the distance from this range, the less chance of obtaining a quality finish.

The above recommendations apply regardless of the nature of the finishing materials, technology or machinery used. If they are followed, quality finishes can be achieved. Ignoring them leads to finishing defects, and fixing it means extra materials and labor, so extra costs.