" " wisno wood furniture finishing

Sunday, November 9, 2014

Epoxy putty

Epoxy putty is the type of putty that uses epoxy resin as the binder. The epoxy resin is mixed with bulking agent as the main components of the putty. The bulking agent is a material with no (very small) shrinkage that function as the ”filling material”, while the epoxy function as the binder that keep the bulking agent to coalesce and hard. There some other materials; solvent, additive and pigment are added into the mixed to give the specific properties of the putty.
The character of the putty is mainly determined by the properties of the epoxy resin. It is a two components material which fast drying, hard, strong with good sanding properties after he completely dry. Epoxy resin is a thermoplastic layer that is strong, hard with very small shrinkage. The epoxy has high resistance to the solvent, thinner and heat. The putty can be layered with any finishing material such as:  nc, water based, ac, pu and even polyester or uv coating after it completely dry.
The epoxy putty is very good material to fix the hole, dent, gap or crack to make the even and flat surfaces. As putty he is very stable, after he won’t, shrinkage by application of finishing material, stain, coating or thinner on it.  Some people use the epoxy putty to fill the pores and grain to make close pores finish. It has very good filling properties that help to fill and close the pores and grain quickly.
While the disadvantage of this putty is that he cannot absorb stain that is applied on. Any stain applied on the putty won’t attach to the epoxy surface. It will lead to color problem especially for the wood finish with transparent color. The putty also does not have color choices; the putty is commonly available in the market with gray or white color. We may add some pigment into the putty to colorize the putty, but the color resulted is very limited. The white pigment color of the putty prevents to get the bright and clear color. Any tinting will give the muddy and cloudy color. The pigment addition is also limited, too many pigment into the mixed will reduce the strength of the putty. Too much pigment in the mix could lead to the crack or adhesion problem to the finish.
At the wood color finish (transparent finish), the epoxy putty on the wood will leave a white or gray which obviously looked at the final finish. We can touch up with glaze or stain to cover the white color of the putty, but it will be take long time and difficult process. Then the uses of the epoxy putty for the transparent woo d finish must be considered carefully. Make sure it don’t, ruin and affect the final color finish looked. 
Epoxy putty is more suitable to be used for the finishing process to wood with the solid colors (paint finish). In the paint finish, the color of the putty won’t be problem since it will be blocked and covered by the base coat or the paint applied on. The epoxy putty is also good choice to fix the metal, resin or aluminum because they usually finished with paint color.

Here are some tips in the application of the epoxy putty
  • Consider the final finish color and looked.
The putty is applied to get the better looked at the final finishing. Make sure the putty is fit the final color finish. The epoxy putty is more suitable to the solid color finish. The epoxy putty for the finishing with transparent wood finish must be done carefully to make sure the putty will not ruin the color and looked of the final finishing color.

  • The surface cleaning.
To get the strong adhesion between the putty and the substrate, then the gap, dent or hole must be well cleaned. Any dirt such as: oil, dust or other material in the gap could interfere the attachment of putty to the substrates. Blow the dent, hole or gap with air pressure to clean the dust or dirt inside. If necessary we can use a knife to open and enlarge the small hole or gap to make sure we can well apply the putty.
  • Application of the putty.
Epoxy putty is composed of two materials, the putty and hardener. Both components must be well mixed with the proper formula to get the strong and hard dry putty. Make sure we follow the recommended ratio according to the technical data sheet. If necessary we can add some thinner to thin the mixed.
Insert the putty into the crack or gap with spatula or knife, make sure the putty fill in the gap completely; then scrap the protrude putty to level the surface. Try to get the level surface when putty is the paste form. The dried putty will be hard and can only be leveled by sanding process which is tough work.
  • Cleaning the excess
Make sure we the putty is only left inside the hole. The excesses putty on the surface will ruin the finish appearance or result to the uneven surfaces. We must try to clean up and even the putty during the application when the putty is still wet because it will be easier done. But after the putty dry, we still need to sand to clean up the putty and get the even surface. Make sure the putty is already completely dry and do a good sanding to clean the putty and get the even surface. Sanding the putty is very important, because the epoxy putty is a two component material that will be hard and insoluble after it dry. We need to use fine sandpaper to remove the sanding mark at the surface. Uneven surfaces or sand mark may appear on the final surface finishing.