Fixing Little Dents and Dings Before Finishing

Tips for finding and filling small dents in wood before applying finish. June 30, 2007

I am using water based finishing products to create a smooth 30 sheen black finish on a flat 5” wide, 10 foot long poplar board and I run 500 LF at a time. We have no problem applying the finish, but when we inspect the boards after finishing, we occasionally find small dents in the wood that we had not noticed before finishing. As we know, black shows everything. I need to know the best way to apply a filler to the wood before sanding - sprayable filler if possible, because the fillers that squeegee on sound difficult to work with.

Forum Responses
(Finishing Forum)
From contributor M:
I would think any auto body spot putty would work good. Just be sure it takes a hardener - don't use the old style lacquer putties that air dry, as they shrink a lot over time. If you want something to spray, check out auto polyester primer. It's basically sprayable bondo.

From contributor D:
Where little dents and defects look like big dents and defects, one trick I use is before final sanding of the bare wood, I wet the piece with some water. Not soaking, but wet (similar to applying a wb dye by hand). The water will raise up a lot of the things that the first coat of wb finish usually does. Then sand it after it dries and continue your normal routine. You don't have to fill it if it ain't there.

From contributor M:
Another thing that actually works pretty good. Use a guide coat before final sanding. I mist a coat from a spray can of black sandable primer on the surface and then sand till it's all gone. It really shows the missed spots fast and sands off easily.

From contributor G:
I second contributor D's method. Saves a lot of sanding. Hot water is what I use.

From the original questioner:
When I read contributor D's information, I thought, well - I have tried water before. Using a wet cloth and going over it with an iron removed dents in finished boards, so I’m going to put some small dents in a board and try it. I also am looking into the polyester primer. I have never used a polyester primer before. The product seems to be marketed to the automotive and marine industry, and the company I spoke with, “US Composites,” didn’t know if their products would be compatible with the water base finishes I’m using. They told me to contact a company called “Evercoat.” I should have mentioned that I would also like the product to fill some of the small knotholes that are found in poplar.

From contributor M:
Maybe you should consider a grain filler. (The spot putty is a lot easier to sand, though.)

From contributor T:
Have you determined what put the dents on the panel? If you are running the stock through any machine with a roller feed or roller/wheel hold down, that will put dents in a panel easily. Out feed roller on a wide belt will do that and you won't see it until later… Check your rollers!

From contributor Y:
As other posters stated, I also use a wet rag for small imperfections in the wood. But I go one step further. I took my wife's clothes iron and put that over the wet rag. It takes most imperfections out quickly.

From contributor L:
Same as contributor Y. By the way, that's not a clothes iron... it's an edgebander :-).

From contributor D:
For steaming out dents, I like to use my burn in knife. It's small enough to pinpoint the heat right where you want it. More precise than the iron.

From contributor E:
I do a lot of pigmented jobs. I stopped using poplar because it is just too soft and it also fuzzes. Go to soft maple and you will do a lot less filling. Every time you slightly bang into something during fabrication and finishing, the poplar will get a small dent that will show up with your topcoats.