Gloss Problem in Wood Finishing.

In the finishing world, the term gloss or sheen is meant by the measurement of lustrousness, shininess, or reflecting ability of a surface. The gloss is scaled from 0 sheen to 90 sheen. The highest gloss, or the full gloss, is the 90 sheen when the surface reflects all (most of) the light that comes to its surface. While the lower gloss is the 0 sheen, when the surface absorbs all of the light received. Basically, the high gloss is resulted by a flat, even, and smooth surface, while the uneven and rough surface will give the low gloss. See our previous article; gloss in the wood finishing.

Gloss is an important element in modern finishing. The gloss will determine the finishing look; finishing with the same color will give a different impression if it has a different gloss. The finishing appearance of the furniture product always needs appropriate gloss instead of finishing color. For example, the carved furniture, the ornamental furniture, or the antique furniture usually need a low or medium gloss finish. While the high gloss is more appropriate for the minimalist and the simple furniture.

Now the gloss at the wood finishing can easily be managed by the selection of the top coat. The top coat as the final layer of finishing is available in any sheen. The finishing people can choose the top coat with the right sheen according to the finishing requirement.

But as a finishing person, sometimes you may face some problems about gloss or sheen in the finishing process. The gloss could be too low, too high, or inconsistent in the finishing. Here are some tips to handle the gloss problem in the wood finishing. 

gloss measurement

1. The gloss is too low.

The low gloss is caused by too much matting agent in the film, an uneven film layer, or too thin film thickness. Here are some tips to solve this problem.

• Always does a good agitation to the top coat mixing 

The proper agitation is needed every time you take some top coat from a pail or drums to make sure the top coat is well mixed and homogeneous. The imperfect mixing will lead to the matting agent being settled at the bottom of the drum or pail. The early use of the top coat may give you the too-high gloss, and the last use will give you the low gloss.

•   The coating film is too thin

The gloss of a finishing is also determined by the thickness of the coating film. The thin film will give you the lower gloss. If you already used the high-sheen top coat but got the low-sheen, then check the film thickness. Make sure the film finish is thick enough to build the right gloss. Usually you need a minimum 3 mill thickness film to build the gloss.

• A good spray technique.

Low gloss can also be caused by an uneven surface due to the dry spray. The dry spray will create dust spray that will make the rough surface and make the low gloss. To get the maximum gloss, you need a perfect, even wet coat to build the smooth, even, and good flow film coating. 

2. The gloss is too high

Gloss is too high and is usually caused by a lack of matting agent content in the film layer or a too thick film layer. Here are some tips to solve this problem.

• Do a good agitation to the mixture of top coat.

Matting agent is easy to settle and stay at the bottom of the coating mixture. Therefore, every time you apply the top coat, you need to agitate the top coat to make sure it is homogeneous mixed. The imperfect mixing will let the matting agent settle at the bottom, and the "clear" top coat is layered at the surface. It will result in the high-gloss film.

•  Be careful when using retarder.

The retarder is needed to slow the drying time of the top coat. The retarder will help to produce a smooth film by improving the “flow” of the top coat. However, the addition of retarder must be carefully observed. Too long a drying time can lead the matting agent too go down and settle at the bottom of the coating film, especially when the thick film is applied. It means the high gloss finishing is resulted since the upper layer of the coating will be the "clear" film that highly reflects the light. 

• Avoid too-thick coating film.

The gloss of the finishing is also influenced by the thickness of the film layer. Too thick film tends to produce the high gloss finish. Then control the coating film; always check the film thickness of the finishing result. Make sure you got the proper thickness; avoid too-thick film. Do a good sanding every time you layer a clear coat to build the even thickness of the film finish.