I recently was asked how to remove a wax blemish from a Corona dining table. The table's owner, seeing that I was puzzled by the question, explained to me that he had attempted to re-finish the piece but apparently missed a small patch of wax during the stripping process. As a result, that small area turned into a black splotch when he put the first coat of stain on. I gave him the following advice, which you may find helpful for any type of discolouration of your dining table.
First, understand that blemishes underneath the finish of any piece of wood furniture cannot be treated apart from the rest of the piece without resulting in a noticeably different look. With the table in question, if the owner missed a small patch of wax during the stripping process, then he also missed the finish underneath. That's why it turned black.
We can't simply deal with the black splotch alone, because a uniform look requires a uniform finish across the entire piece. Therefore, even though it's a pain, getting rid of that blemish properly required the item be completely stripped down.
This table was a Corona piece, so it took some extra care. Corona furniture is made from Mexican White Pine, which is terribly hard to finish evenly. The wood is so porous, it absorbs stain very rapidly. Any sanding between stain coats affects the porosity and adds to the difficulty. Woods like cherry and oak tend to be more forgiving.
To treat a piece of blemished Corona furniture, you must first use a chemical stripper to remove the current finish. You need to get all the way down to the bare wood, so if the finish is especially stubborn, steel wool or a rigid brush may be necessary to get the job done. Just be sure to follow the instructions on the container and avoid digging into the wood.
Once the piece is completely bare you may sand it down, but do it ever so gently. Sanding too hard will create areas that will not absorb the new wood stain as easily as others, causing an uneven finish. Also be sure to clean the wood thoroughly with a damp rag to remove any residual dust.
After the furniture is clean and dry do a visual inspection to make sure you haven't missed anything. Then follow the same procedure you would for any other piece of Corona furniture.
Apply your first coat of stain, buff it with a clean cloth, lightly sand, and repeat until you reach the desired result. Be extra careful when sanding between coats. Finally, give the stain the proper amount of time to dry before applying polyurethane or another sealer.