" " wisno wood furniture finishing: Sponging technique for wood finishing

Monday, April 18, 2011

Sponging technique for wood finishing

The sponge effect in the furniture finish

Sponging is a technique application finishing material using sponge. Sponging is one of the finishing techniques in the finishing process in the solid colors (paint finish). The sponging is well known in the murals or faux painting. The finishing color produced is the uneven staining color with specific patterns that very special and unique. In the wood finishing the sponging technique is mostly done for the application of glaze over a base coat or paint to produce a finishing with  special appearance.
Here is an example of application the glaze with sponging technique in a finishing process. The finishing system is NC (nitrocellulose) finish; all the base coat and clear coatings used are the NC type. Glaze used is also the regular glaze that proper to be used in the NC finishing system.
 
The finishing process is as follow:
  • Base coat application
Base coat is the solid color stain that forms the color base of the finishing. In this finishing process we use the NC base coat. The color used is off white (white color with little amount of brown). The base coat is applied by spray to overall surface. Spray the base coat evenly to cover the wood surface. Wait until it dry, and then sand the base coat to cut the wood fibers raised. One time base coat application usually is not enough to make an even color, and then we need to spray the base coat two time or even three time until we get the even color. Wait until the base coat dry and then sanding the base coat to obtain a flat and smooth surface.
  • Sealer application.
Sealer is applied on the base coat to produce a smoother surface before the glaze application. The sealer application will resolve and remove the sanding mark  in the base coat to make the smooth and even surface. The sealer coat also will prevents the “too deep penetration” of he glaze and make the glaze application can be easier controlled.  Apply the sealer by wet spray overall the surface. Wait until the sealer is dry. 
  • Glaze application
The glaze application is the main step to make the finishing looked. Use the glaze with the right color to produce the desired color finishing. Consider that the final finishing color is obtained from the combination of the glaze color and the base coat color.  While the finishing looked is highly depend on the sponging technique.
There are many sponging technique and each will create different effect. There are also many sponge type available to do the sponging. The finishing looked is depending on the sponge type and pattern. We may need to do some experiment to fine the right sponging technique according to the finishing looked desired. The sponging technique need to done consistently. We need some time to do exercise to get used with the technique. By enough practicing we can find the best way to get the desired result.

 glaze is sponged little by little

Generally there two model of sponging technique. The first way is by wetting the sponge with the glaze and applied it to the surface little by little. Wet the sponge with the glaze then pad the sponge to the surface. The padding should be done consistently and bit by bit until the entire surface evenly coated with the glaze. 

glaze is applied on the surface and sponged to get the desired effect
The second way is by applying the glaze evenly to all surfaces (it can be done by brush, spray or rag). Then the sponging effect is created by pad the sponge on the wet glaze. If the glaze is dry already, then the sponge can be wetted with the mineral spirit or thinner glaze.
After we obtain the desired appearance then we have to let the glaze is dry completely. The drying time of the glaze can be varied from 1 hour to 1 day depend on the glaze type and the thickness of glaze layer.
  • Sealer application
Apply the sealer after the glaze is dry. The sealer coat serves to bind and protect the finishing effects that have been generated by the glaze application. Avoid spraying sealer too thick, since the risk off sagging that will  destroy the sponge effect. Apply the sealer with medium wet spray technique. Spay two coats of sealer to make sure we give enough layer on the glaze. Let the sealer dry and then scuff sand the sealer.
  •  Application of top coat
Top coat is applied by spray evenly to the overall surfaces. The top coat is wet sprayed to perform the smooth and even surface. Many sheen can be used, but this finish mostly is coated with semi gloss or semi doff top coat.

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