Touching Up Hairline Cracks in a Waterborne Finish

Expert advice on hiding a crack that appeared during transport. October 19, 2013

Question (WOODWEB Member) :
I've noticed this before in cabinets where the plywood center panel changes color (yellow - usually when a simple clear coat is used). I'm not sure if this is because a yellowing finish (NC lacquer or poly) was used or if it's a function of the plywood. I need to build/finish some shaker type doors and was hoping to do a clear (water white pre-cat) finish. I do not want this kind of discrepancy between stiles/rails and the center panel. I've done these types of doors before but stained them and I don't notice a problem with the ply panels.

Forum Responses
(Finishing Forum)
From Contributor E:
I think it’s the type of wood in the stiles and rails and the plywood. In the one component you are dealing with solid material which has been harvested and processed in one way and the panels being veneer are harvested and processed in a very different way. Sometimes there is a color difference, sometimes not. Solid wood will come from one forest and the veneer from another. If you really want to have a match you can always lay up a solid wood panel but it is time consuming and takes machinery. If you want a fine piece of furniture that is maybe the way you should be heading. Don’t compare anything to the mass produced products as they again are made in different ways.

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From contributor D:
The veneer is slip matched flat cut veneer. In that process the tree is cut into thin veneer strips and stacked as it is cut from the log. The veneers grain orientation is to allow the grain cathedrals to be the star attraction. The stile and rails appear to be 1/4 sawn, which will highlight the rays on the grain. Cuts that differ this much will expose differences in the wood, even if they were cut from the same tree. If you are attempting to have a perfectly matched piece you will need to have all the wood cut with the same grain orientation.

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From contributor F:
Even if you had wood from the same tree as your veneer you would still see the difference over time. It has to do with the way we see things and how light interacts with the wood. With modern veneers being so thin we not only see the veneer, but we see light reflecting off the base material as well. This makes them look different in good light. However, even if you get the match perfect between solid and veneer up front over time it will alter. The oxidation that occurs with exposure to light will amplify the difference between solid and veneer causing the yellowing affect. It's not the finish as the same finish is on all the components.

To avoid it your best bet is using solid wood for everything. Of course that's not really practical, so one thing that can help is veneering your own panels. By applying your own thicker veneers you can keep the color much closer and keep to a minimum how much it changes over time. Otherwise if you go with factory veneered panels you can count on seeing that color change.