Originally Posted by bobsmyuncle
I have to agree that using 0000 steel wool may be the way to go. However, we don't know if the finish has a flat, satin, semi-gloss or gloss sheen to it. Beyond a semi-gloss sheen, then steel wool isn't going to do much good as far as blending in with the existing finish. Furthermore, it might be necessary to fill the crack slightly with just a little bit of spray lacquer and also use some very fine abrasive (sand) paper in order to smooth out the crack that has been filled before using the steel wool. The process of filling up and sanding a crack can take more than one time before it looks right to proceed with buffing out the area. A 240 to 320 grit abrasive paper might be appropriate to use before using the steel wool.
If the sheen to your finish is satin to a semi-gloss, then when you use the steel wool, some kind of lubricant should be used when rubbing out with the steel wool. Since the finish is lacquer, then water, mineral spirits, even a light furniture polish or a paste wax might be used as the lubricant.
If the sheen to the finish is flat, then it will be necessary to rub it out using the black, wet/dry abrasive paper such as might be used on automobiles. This would be in order to achieve the flat sheen look to the finish.
A light spray of lacquer of the appropriate sheen can be sprayed on the area after any sanding is done in order to fill up the crack. But, be sure to spray very lightly. Deft lacquer is a favorite to use by people who touch-up furniture. There are also other, quality brands.
No matter what, when touching up finishes that are in the sheens of flat to gloss, then more than just the very small area of the crack is involved with the touch-up. What I am saying is, that it is best to be rubbing out an area with the grain of the wood and in a much larger area than is comprised by the crack in order to make everything look just right.
If this finish is a gloss sheen, then it will require different procedures for touching it up that have been described above.
The touching up of finishes is an art in itself. If someone is not used to doing it, then it is best to call a professional if the piece is really valuable and/or you care greatly about how it looks.