By: Mitch Kohanek
“Spot repairing” wood brings to mind so many variations after so many years of repairing damaged objects. Damage to white wood, damage to newly finished wood, damage to just the coating, damage to the finished wood and coating, restoration of old wood and the heritage antiques worked on during my internship at the Smithsonian Museum.
Different levels of damage require different levels of skill.
Repairs happening in the shop where the customer has not seen the damage is a comfortable place to be. Repairs being worked on outside the shop can really be challenging, having fewer repair tools and working on damage that has probably already been seen by the owner.
The first tools needed in either category is your level of talent, creativity and knowledge of your materials. Repairing in house in a manufacturing environment the repair system can be rather straight forward. If you ask 10 “Road Warrior” repair technicians (those who do repairing at the site of location) how to repair any given damage, you will get a variety different answers.
One example of damage is one that penetrates both the coating and the wood. The repair kit needs to first include something to refill the void in the wood. The higher skill level is associated with the coloring on top of that fill.
There are a host of materials that will fill the void. The size of the damage and the location of the damage will dictate which one of those is a better choice. Soft wax fill sticks, hard wax fill sticks, hard plastic fill sticks, low sheen sticks, high sheen sticks, shellac sticks, polyester fills, epoxy sticks and wood putty to name a few.
Sometimes a “burn in” is required which means the repair stick has to be heated with a hot knife and dropped into place. There are several choices of heating knives to choose from. There are two very different burn in “systems” we will be discussing, each requiring two different skill levels.
All of these sticks come in a variety of colors to correspond to the existing color of the object. The more you know about color matching and performing in-painting (graining), the fewer colored sticks needed. One of the more valuable fill sticks is one that is totally transparent. Excellent stick for dents in the wood and the coating has flexed with the wood with no color loss.
Once the void is filled, the excess needs to be removed and the surface leveled without causing any more damage to the coating or substrate. Don’t forget about the reestablishing the earlywood pores with an open pored finish.
The fill stick now needs the proper protective coating applied on top of it. Padding, brushing and spraying are your options for coating application. Solvent and waterbase coating are your two choices. Compatibility of the repair products and coating should be taken into consideration.
Once the void is filled, leveled and sealed the real “artistry” begins with the in-painting (graining) and creating a faux finish on the repair. The goal is to recreate the color, grain pattern and texture that used to be there.
Depending on the size, shape and location of the in-painting there are different tools to choose from. Touch up markers and graining pens are handy and do not require very much skill. Hopefully you have the right colors and ones that work.
Highly skilled repair technicians rely on pigments and/or dyes for coloring/graining/in-painting using a variety of different sized brushes. Doesn’t matter if it is a transparent, translucent or opaque finish that you are working on. Color is color. The more you know about color, the fewer colored pigments and dyes you need. Plus the fewer colored repair sticks you need.
Color matching is a challenging art. Sheen control can sometimes outweigh the stress of finding color. Off the gun low sheen finishes are a real challenge. Sheen has its nomenclature such as gloss, semi-gloss, satin, flat, dead flat. More accurately sheens are given numbers such as 80 degree sheen (high sheen), 50 degree sheen, 20 degree sheen, 10 degree sheen (low sheen), etc.
It is convenient to have aerosol cans that are labeled with the sheen number they produce. For mechanical sheen control adjustments, steel wool and synthetic steel wool (abrasive pads) have certain grits and sheens associated to what they will produce. A rubbed out satin sheen does not look much like a sprayed on satin sheen.
In order for damage to “disappear” all of these steps need to be executed to its highest degree. In reality making all repairs “disappear” is not reality. With so many variables you need to recognize what actually can be accomplished. The greater the damage, the greater the skill needed.
All of you who have walked this road know that WE are OUR worst critics when it comes to knowing when to quit working on the repair. Some go buy the 6” by 6’ rule.
What I have learned is that when that little voice in the back of your head says “Just one more grain line, just one more bit of color”………. Ignore that little voice.