Thinner is the material that is used to thin the finishing materials and to set specific properties desired during the handling, application or storage. The pure finishing materials (pigment, paint, filler, coating, resin, etc.) are ussually solid material or thick paste with high viscosity. The pure finishing material is very difficult to be applied or even handled. Meanwhile the equipment to apply the finishing materials such as: roller, spray gun or even brush can be used for the thin (low viscosity). The thinner is added to then into the pure finishing materials to make the finishing materials in the liquid condition and to accord the viscosity material to the finishing equipment wishes. Almost all finishing materials need thinner. The main function of thinner is to dilute the finishing materials and reduce viscosity, but thinner is also added to build some characters of the mixture of finishing materials. Some special character such as: the drying time, film flow, the penetration, and the strength of the finishing materials (in limited range) can be set with the thinner chosen. The amount of thinner that is added in the finishing materials is also used to adjust the concentrate of the finishing materials during the application. Every step of finishing process needs a certain amount of finishing material that laid on the surface to get the desired result. To adjust the thickness of finishing material is done with thinner. If the material is thick, then we can cut with thinner to get the right concentration.
The coating such as sealer and top coat is a mixture of resin with 1 or more resins as the main ingredients, plus some additive substances. The composition of resin and additive mixture varies depending on the type of finishing material such as: polyurethane, nitrocellulose, acid curing, acrylic, alkyd, vinyl, etc. and also depend to the brand. While the stain as a mixture of pigment and binder are also has different composition for each type and brand. Like the finishing material, the material for thinner is very specific depend on the finishing material that need to be solved. Therefore, each type of top coat, sealer, and stain actually need different thinner. Thinner for clear coating is usually called as lacquer thinner, is designed to make the clear coating flow well, and get the right viscosity depend on the application.
The selection of thinner was also used to set and adjust the drying time by finishing material application. The drying time of the finishing material is need to be set depend on how the application. For example for the brush application, we need the materials that need longer time to dry to make the even surface and reduce the brush mark. While the finishing materials for spraying application need dry faster, the longer dry will reduce the speed of the finishing process and also tend to sagging. The selection of the thinner should also look at the conditions in the finishing room where the finishing process is done such as: the air temperature, air humidity, the production speed, the step of finishing and the facilities in the finishing room.
The thinner will entirely evaporate during the drying of finishing materials. He is just like a vehicle to deliver the finishing materials to the finish surface in the application. The thinner will be entirely exhausted and nothing is left at the finish surface. So it needs to be understood that the uses of thinner in the finishing process must be set to be as little as possible. The more solvent is used it means that more money is wasted by being thrown into the air and a less film thickness is being deposited on the work. In judging the final cost of finishing, the original cost should not be considered as the price per gallon alone, but number of coats, the labor cost, time of overhead, the total quantity of material needed to produced the finished, quality of dried films and many other points
Although only the vehicle, but the thinner selection is one very important thing because it will affect the drying speed of the finishing materials and finishing processes and could also be influence the strength and quality of the resulting finish. There are many problems could arise because the uses inappropriate solvent on the other hand, there are many adjustment in the finishing process can be made by choosing the thinner used.
Thinner is made from a mixture of solvents, (latent solvent) and diluent. Solvent is a substance that serves to dissolve a finishing material. For example solvent for nitrocellulose is: m.e.k. (methyl ethyl ketone), acetone and buthyl acetate. While latent solvent is a substance that helps dissolve when mixed with a solvent. Latent solvent can not dissolve the material, if not mixed with solvents, for example nitrocellulose latent solvent is methanol, isoprophyl alcohol and butanol isobuthyl. The solvent and the latent solvent are the main ingredient for thinner, some peoples called them with active thinner. The solvent and latent solvent usually are expensive material then into the thinner is also added another ingredient called diluent, a material that dissolves in each other with solvent but can not actually dissolve finishing materials. Diluent is usually the ingredients are cheap and added to the mixture of paint thinner to reduce the price of the thinner. The materials that can be used for solvents, latent solvent and diluent are highly dependent on the type of finishing material.