First, I'm posting in the open forum, because I think others might also benefit from Dave's knowledge.
I have a 1972 TR6. The dash is plywood, with a walnut veneer. The original finish was some kind of hard varnish or poly, which crazed, and looked plastic. When I removed it some years back, with a razor blade, I measured it, and it was .01" thick. Anyway, the only finish I have used since then is BLO, which I reapply thinly about once a year or so. No big deal, pad it on with a rag, wipe it off, looks ok, but feels less than satin smooth. The glove box door has a hairline split in the veneer, this has been present for years. I don't sand between applications because the veneer is pretty thin, and I don't want to take it all apart again, those old gauges and wiring don't do great with too much handling.
So, to get to the point, Dave, I believe you've redone the woodwork on some fine older cars. Do you have any suggestions for another way to topcoat / protect the dash? Would heating that hairline with an iron and trying to reactivate the glue likely be helpful, or be more likely to cause more problems? The dash is OK as is, but if there's something better I can do, I'd like to hear about it.
First the car with the current and the future owner:
And the dash: