Drying time for wood finishing

Drying time

Finishing process is the process of apply the coating material to a surface. Finishing materials when it is applied in a surface is wet and soft, and then by the time the layer is increasingly dry and become hard to make a film coat to protect the underneath surface.  Finishing material is a chemical that requires a certain time and certain conditions to be dry and become hard. The drying process of finishing this happens in several ways depending on the type of finishing material used. And because of this reason the drying time vary depending on the type of finishing materials used.

The drying time is the time required for a finishing material to be dried and become hard. In the process of drying the finishing there is at least 3 state of the drying: touch dry, dry for sanding and dry for packing.

• Touch dry 

Touch dry is a condition when a finishing layer is dry enough so it can be touched without any problem. The touch dry film coating is dust free condition, but it is still weak film layer. It is very easy to damaged by little stress or scratched. From the wet coat until the touch dry state, the finishing surface cannot be touched and get dust. Any dust or dirt falls to the surface will stick to the surface and create the dirt and rough on the finishing surface. During his touch drying time, the finishing surface should be placed in clean and dust free room to prevent the problem from the dust. In the sealer application the dust or dirt is not really big problem, since it will be sanded and coated with another coating. The dirt or rough surface will be clean up with the sanding process. But for the top coat as the last layer in the finishing process, the dirt is not allowed. Since that we require a clean room and free of dust as the drying room for the top coat. Some finishing material such as nitrocellulose has short time touch drying time. For this material we don’t need a special drying room. But some material such as polyurethane have long touch drying time, will need a special dust free drying room.

• Dry for sanding 

Every clear coating such as a sealer and top coat always need to be sanded when he followed by another clear coating application. When it is sanded, the film layer must be dry enough so the sanding process can be done easily with good results. The time required of the finishing layer reach the condition when he is able to be sanded without any problem is the drying time for sanding. The sanding drying time determine the speed of the finishing process. In the design of a finishing room, the enough space should be provided to place the products from the wet condition until they reached the condition dry for sanding.

• Dry for packing.

After finishing process is done then usually a product can be delivered to the purchaser or the show room. To deliver to the buyers who are in near place, then the delivery can be done with a vehicle such a car or truck, and we may don’t need to pack the product. But if the product is delivered to a far place then the product requires a good packing to keep the goods secure. Before a product can be packed the finishing layer must be completely dry. The drying for packing is more than just a touch dry, because while a product is packed the goods are covered tightly so does not allow solvent evaporation process occurs anymore. The delivery is also high risk of tortured in handling, so it needs to make sure that the finishing is completely dry before being packed. A finish that has not been dry enough is highly risk to get problems such the paper attached and print to the finishing. 

• Drying for stain and glaze

When we talk about drying time above, then it is more concerned about the clear coating material. The other finishing materials such as stain, filler and glaze are also a chemical which requires sufficient drying in a finishing process. A layer of clear coating that has not dried relatively easily to be detected, because if we continue following the process of going directly visible problems that arise, such as the finishing damaged.

But for the stain, glaze and filler the layer of material is usually thin layer, since that it very difficult to be seen physically whether the layered material is dry or not. Layer of stain can be touched with no problem even his condition was not completely dry. Meanwhile, as well as other finishing materials, this stain should also be dry enough before followed by further application. Problems will arise if the stain is not dry if or coated with sealer top coat. The solvent in the there will be trapped in the finishing layer, and will cause finishing problems such as adhesion problems, hardness, or other problems such as blushing or clarity on the looked. To minimize the problem with the drying, we must know the type of materials used. The thinner based stain is relatively very quick drying normally solvent based thinner just need a few minute to dry in a room temperature. But for oil stain or glaze which is use oil or mineral spirit as a thinner it take about 1 hour to completely dry. Check and read the specification of the materials and follow the instruction to make a safe finishing process.

Paint testing manual. Physical and chemical examination of paints, varnishes, lacquers, and colors. 13th Edition. Published b ASTM. 1972 Edition