Gloss problem in wood finishing.

In finishing world, the term of gloss or sheen is meant by the measurement of lustrous, 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 reflect all (most of) the light that come to its surface. While the lower gloss is the 0 sheen, when the surface absorb 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 the modern finishing. The gloss will determine the finishing look; the finishing with same color will give different impression if it has different gloss. The finishing appearance at the furniture product always needs appropriate gloss instead or finishing color. For example the carved furniture, the ornamental furniture or the antique furniture usually need the low or medium gloss finish. While the high gloss is more proper to 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 people, sometime we 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 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, uneven film layer or too thin film thickness. Here some tips to solve this problem.

• Always does a good agitation to the top coat mixing 

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

•   The coating film is too thin

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 use 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 we need minimum 3 mill thickness film to build the gloss.

• A good spray technique.

Low gloss can also be caused by 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, we 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 is usually caused by lack of matting agent content in the film layer, or too thick film layer. Her 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 we apply the top coat we need to agitate the top coat to make sure it is homogeneous mixed. The imperfectly mixing will let the matting agent to settle at the bottom and the "clear" top coat is layered at the surface. It will result to the high gloss film.

•  Be careful when in using retarder.

The retarder is needed to slower 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 drying time can lead the matting agent too go down and settle at 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 reflect the light.  

• Avoid too thick coating film.

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