Replies

1. 
   SgianDubh | Feb 06, 2009 11:35am | #1

   You have a contaminant of some sort on the surface of the maple mouldings, but not on the beech wood. It is likely to be a wax, oil or grease of some sort. It is slightly possible that you have silicone on the surface, but this is more likely to be the case if you were refinishing some old furniture that has been polished with one of the spray on wax polishes that contain silicone.

   You will have to establish for yourself where the contamination came from, and what the nature of it is. Ask yourself what was different in the processing that caused the contamination on the maple, but not the beech?

   If you feel you need to start all over again to improve on what you have then the following is as good procedure; it's not the only one, but it will work.

   • Strip the existing finish using a methylene chloride stripper and prepare the surface again.
   • Wipe it down thoroughly with a degreaser, eg, cellulose (lacquer) thinners.
   • Spray on a light coat of dewaxed clear (blonde or super blonde are alternative names) shellac which is noted for its ability to stick like sh*t to a blanket so to speak. An alternative to the shellac might be a vinyl sealer if you find it hard to buy shellac.
   • Spray a couple of coats of your pre-cat lacquer over this, assuming it is pre-cat you are using.

   Thorough degreasing  after stripping the existing finish as mentioned above may in itself clear the contaminants sufficiently for you to spray your cellulose based polish over the bare wood- the degrease and shellac routine is a 'belt-and-braces' approach.

   The dewaxed form of shellac is not important under pre-cat lacquers, but it is if you use it under some other types of film forming finishes, eg, water based. But the point is that dewaxed shellac provides a base that any other film forming finish will adhere to. Slainte.

   Richard Jones Furniture

2. 
   hammer1 | Feb 06, 2009 02:21pm | #2

   Your description of 1/2" diameter is a bit strange. Normally with silicone contamination, you get an orange peel type of situation. How would you get silicone on fresh milled lumber? It hasn't been an ingredient in furniture polish for many years. Fish eye reducer is often added to your lacquer if you suspect silicone but that's usually when refinishing older furniture.

   What are you spraying with? Could you have something from a compressor, oil or water in the line? Do you use a separator? Another possibility could be something you cleaned the gun with. If you used a freshly sharpened cutter and it was in a protective dip, there is often an oil on the cutters, some could be in a bearing if there was one.

   If it's only a few spots on one or two pieces, I'd think back to anything you may have done in the shop. Did you use a sanding sealer? Add thinner, clean something else in the shop. Did your dog sneeze, could you have used a contaminated container, did you use a tack cloth, did you sticker the moldings, could something have gotten on the lumber during transport, the list goes on.

   Beat it to fit / Paint it to match

1. 
   nagar1 | Feb 06, 2009 03:05pm | #3

   Thanks for the replies. I suppose there must have been some contamination on the pieces of maple, but I can't imagine what it would be. All the pieces were milled at the same time, as well as the beech, and were sanded before they were lacquered. I am always very careful when I prepare wood for lacquering, but I suppose something could have been on the wood. It is a bit strange, because I was using maple from the same batch to make some doors and drawer fronts for a bathroom vanity and the same thing happened, only not so much. This happened a few weeks before I made the maple trim.

    

2. 
   HowardAcheson | Feb 06, 2009 06:01pm | #5

   >> Your description of 1/2" diameter is a bit strange. Normally with silicone contamination, you get an orange peel type of situation. How would you get silicone on fresh milled lumber? It hasn't been an ingredient in furniture polish for many years. Fish eye reducer is often added to your lacquer if you suspect silicone but that's usually when refinishing older furniture.Actually, silicone contamination is characterized by "cratering" or what is known as "fish eyes". Orange peel is most often a symptom of improper air pressure or distance of the nozzle from the surface being sprayed, or temperature/humidity problems. Also, a number of supermarket "furniture polishes" and cleaners contain silicone. The most common is Pledge. Some car polishes also contain silicone or other contaminates that have negative impacts to finishes.Like Richard I would suspect silicone contamination but it could be some other contamination also. The fact that it happened previously on the same batch of wood would lead me to believe that the batch was contaminated before it was purchased by the original poster. If possible I would try to get the lumber replaced. It that is not possible, then the first finishing coat should be a dewaxed shellac barrier coat. Dewaxed shellac will stick to anything and anything will stick to it.Howie.........

1. 
   hammer1 | Feb 07, 2009 01:18am | #6

   I had my first experience with silicone contamination back in 1970. I stripped and refinished a large, multi leaved dining table for a local physician. I used nitrocellulose lacquer. The surface came up like the surface of an orange only not as rough. I had no idea what happened at the time. I had prepped, washed and sanded with the fervor of a youngster attempting perfection. There I stood with egg on my face and a very expensive table that wasn't acceptable. We didn't have the sources of information we have now back in those days. It took me quite a bit of research, by knocking on doors, to figure out the problem and learn about fish eye reducer.This was a moonlight job I took on to augment my meager hourly cabinetmakers wage. I spent late nights and weekends with table parts in the living room, kitchen, hall and any other place I could find in my small apartment. I was rather down when it turned out so bad. It was more nights and weekends to strip and start over. I guess it was all part of paying my dues. The table was pecan and I was still hired to do other woodworking jobs for the customer. Very understanding. I was a kid, often learning the hard way. I doubt that the OP has silicone contamination on freshly milled moldings but I don't have any suggestions for what the problem may be. It sounds like it's only in a few spots. He will have to think it out. Adding fish eye reducer could be his best bet since he already has a couple of coats on the project. Beat it to fit / Paint it to match

1. 
   SteveSchoene | Feb 07, 2009 01:23am | #7

   I'm not a fan of fish-eye remover, especially if we are not entirely certain about the problem being from silicone.  The reason is that once you add fish-eye remover (which is basically silicone) you are pretty much guaranteed to have a silicone problem in the future because of the challenges of getting rid of it. 

3. 
   oldusty | Feb 06, 2009 06:00pm | #4

     nagar,  

         I have had similar areas show up also several times .

       What processes or surfacing methods did the suspect boards  go through .

       Did you use a shaper or powerfeed ?

      Sometimes when I use the powerfeeder on the shaper I wax the surface of the shaper table just in line with the footprint of the stock , to reduce friction and it helps the wood glide smoothly , if I don't sand the area that made contact with the wax the same result can happen as your's. If you used paraffin wax on any of your table surfaces it is possible that some extra got on the wood. Is the problem in a detailed area or is it on the flat surfaces ? If you can just scrape and sand to raw wood and recoat .

        regards  dusty

4. 
   ring | Feb 07, 2009 05:32pm | #8

   In addition to what has already been written -

   1. You can get silicon contamination just from storing open tubes of RTV sealant in the same room with your finishing work.

   2. The same kind of "craters" can also appear if you are working in an unheated space, or if your lacquer is stored in a cold place. In the wintertime (even in Israel) you need to bring your lacquer into a normally heated room the day before you use it.

   David Ring

   http://www.touchwood.co.il/?id=1&lang=e