cauls caused discoloring?

[Bob Riefer]

I built a piece for our new office at our home with a top of ambrosia maple. Finished with danish oil.

Since the piece would sit as ready-to-assemble components in my shop for a long time before final install, I used cauls to keep the top flat while I waited.

Yesterday, when I finally installed in my office, the spots where the cauls were placed are very noticeably lighter than the rest of the top. I ended up sanding and re-applying oil to the entire top to remedy the situation.

In the future, how should I store a top in a situation like this so that I can avoid the issue?

Thanks!!

Bob R.

[Charles Taylor]

I'd imagine the top (the wood, the oil, or possibly both) darkened a little with exposure to light and/or oxygen, and the parts covered by the cauls did not. Perhaps put a cover of some sort over workpieces that will remain in cauls for an extended time. (Let dry first if a finish is applied.)

[glenn bradley]

Agree on irregular exposure due to the cauls being present as the problem. I can't say if or when the problem may have cured itself once the whole thing was exposed. I try to make parts not to far prior to assembly or sub-assembly. Tops I do just prior to finish and install. Drawers tend to come dead last ;-)

[johnny means]

You could have just waited. Eventually, the light spots would have acquired the same darkened tone

[Andrew Pitonyak]

Were the cauls wood? Might they have absorbed / leeched some of the oil from the wood?

[Bob Riefer]

Good stuff, thanks guys.

The cauls are wood, with clear packing tape to prevent glue sticking etc.

I had a small window of time to crank out this top... and then supply chain delays made our home remodel slip by 2 months... So, I had planned to finish and install the same week and it became a long wait instead. Would not plan it this way on purpose in the future.

That said, if I was forced to build and keep a top again, I think I would skip applying finish and keep it covered with the cauls in place until it's "go time".

(also, good to know Johnny that the tone would likely even out on its own as well)

[Adam Herman]

a similar situation happened to me when doing a bunch of blue pine trim work. I just put the newly machined pieces in the sun for a hot day to get the color to match the stuff that was already hung for a couple months.

[Jim Becker]

Light exposure as has been noted...

[Tom Bender]

Triangular cauls would leave only a line. Move them every week.