" " wisno wood furniture finishing: Matting agent

Friday, June 29, 2012

Matting agent

Matting agent, flattening paste or flat paste is an additive material that is used to reduce the gloss of the resulted film produced by a clear coating (top coat). The pure coating is made of a resin mixture that will produce a clear and high gloss film when it is applied at a certain surfaces. When the coating is first time invented and introduced in the wood finishing, then it is quite difficult to make the finish with low sheen. The low sheen finish was made by adjusting the film thickness or rub the dry film resulted. But now with the matting agent additive, then we can make a finish film with the desired gloss by using the proper top coat. With the addition of matting agent, now the top coat can be made and is available in many gloss level. Then now, every finishing people can easily choose the top coat with the proper sheen according to the finishing requirement.  
The first matting agent was made from the silica that was finely grounded and pulverized, but now with the development of chemical technology there are some other materials are developed to be used as matting agent (matting agent additives). If the paint is colored, then the pigment color also can do as matting agent. The matting agent works by refracting the incoming light at the coating film to lower the gloss of the finishing film. (The gloss in the wood finishing).
Now most of the modern top coat are produced and sold with some matting agent inside according to the gloss of the top coat. But we still can also buy the matting agent material to adjust the sheen of the top coat gloss ourselves. To set the gloss level of the top coat we can also mix the top coat with different glosses with the proper ratio.

 matting agent is refracting the light at the film surface

The addition addition of matting agents in the top coat is relatively easy and quite common job in the finishing shop; however it must be done properly. Here are some things need to be considered when we need to adjust the sheen by adding matting agent into the clear coating.
  • Read the specification of the clear coating and matting agent.
Matting agent usually is sold in the form of viscous paste, with some resin in the mixture. The pure matting agent is powder which is very light dust; it is very difficult to be handled and mixed in the thick mixture of top coat. Matting agent that is packaged in a paste form will be easier to handled and added to the top coat mixed. But since there some resin in the mixture, then we must make sure that the matting agent is compatible with the clear coating resin mixture. There are many type of matting agent as well as the type of clear coating. What we need to do is make sure we mix the same type of matting agent and the clear coat. We can ask for the technical data sheet of the material or get information from the finishing material supplier.
  •   Make calculation to find the amount of matting agent to be added.
To get the films with proper gloss, we must add the matting agent in the right amount. Too much matting agent will produce too low sheen; while too less will produce high sheen. Then we need know the amount of matting agent to be added to the top coat according to the sheen we want. We can ask the paint supplier to find the proper amount of the matting agent we need. There should be a chart or table showing the correlation between the percentages of matting agent in a mixture with the gloss of the resulting film. Use the information to calculate the amount of matting agent we should add in the top coat.
  •  Do a good agitation and filtering.
Mating agent essentially is light and fine powder, therefore he quite difficult to get in and mix with the paint which is a viscous mixture. The matting agent is often precipitated and left at the base of the top coat mixture. To produce a perfect mixture then an intensive mixing and agitating is needed. When we add the matting agent, then the addition should be done little by little together with good agitation. After all of the matting agent has been added and mixed with the top coat, then continue the agitation, and make sure the matting is well mixed with the top coat.
Although we already doing the well mixing and agitating, there may be some matting agent powder are precipated in the top coat.  Then we should filter the top coat mix before apply it. Add some thinner to the mix to reduce the viscosity and then filter it with the fine filter before apply the top coat.
  • Make some test and trial before doing the application on a large scale.
Top coat is a mixture of resin; we never know the result before it has been applied. Then every time we do some changing we need to test it. Do the mixing in small amounts, record the formula that we use, and apply the coating to a panel or a small item product. See and observe the result, if we get the result in accordance with what we want, then we can use the same formulation and step to the large scale production.

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