lvlagneto

You can spread plaster too, with a butter knife no less. Bondo putty fumes are intense (but you could work with a window open or in a spray booth). I've never used it in great quantities (for a cast/impression, or massive hole filler), only for very small things, to fill bubbles or pores in resin. Bondo spray primer is also good at fine hole filling when lightly sanded. The plaster cast is drying now.

Please don't invalidate your previous advice by recommending Marmite. I'd rather eat the plaster cast.

Right, I don't want to work with clamps blocking my path.

I can do a small cast of the button area for clamping/working. The area is more forgiving since it's a flat glue zone.

I have a section of matched maple patch material drying now, and some replacement purfling. The torn off button half is actually glued back into position already. I'll only be using hand pressure on a leather pad as I remove material over the cracked area and fit the patch. The paper idea is good, may do that before going to sleep. It seems valid. With a soundpost style patch at the button, it's as babied as this thing can get.

will do

Looks like the scroll was a worm's lunch as well, which might explain the graft pop.

Glad it worked out.

Got it. It's tempting to do half, but I understand the strength idea and intuitive fitting. I see that the patch here is also two parts. Easy enough to do, just curious if there is any future advantage.

Totally possible to do... didn't know if it's worth crossing the centerline and removing undamaged material. What's the max ~ % depth into the plate for that patch?

There's no rush, it's just my preferred material. Thanks for the link, and the offer.

Looking this morning, wishful thinking. You're right about where the mortice falls over the crack - right on it, and not enough button wood reaching past it into the plate. A flat straight patch would be easy to carve and limit to one side of the plate, but we'd see the doubling. I could scoop it a bit to reduce that. Any thoughts on patch shape and location, and taking it across the centerline?

You get a 50% discount by it being Australian currency. Here's a profile shot which might be helpful...

What do you consider a patch near the button to be? I want to be sure we're talking about the same thing. I'm familiar with smaller "tub" style patches near the button, and also more extreme doubling, a T mushroom type configuration for a patch or graft. Again, images are not the instrument, just mocked up to illustrate for now. This is a full big patch/graft photo to show a huge nuclear option patch. The drawn lines show the existing cracks/glue line, and dotted lines indicating where a possible inlaid patch could go. I was thinking oval/tub at first, but you get the idea... some trough shape will be used for the inlaid patch. I know that the crack is slightly angled as it goes through the plate, so we'd be removing original "holding wood" from the button interior. I'll take a better look tomorrow with the block in place, and possibly get photos if I can.

The drawing is the best that I can do at the moment. If I can get photos tomorrow, will do. A "tub patch" is like a soundpost patch somewhere else on the instrument. Imagine a shallow tub shaped soundpost patch within the button area (but you'd only need half of it in this scenario = 1/2 of a half tub shape). It seems like a shame to remove wood that is perfectly fine on the other half of the plate, to support the broken half of the button. The way in which the broken half of the button is shaped/placed like a repair/graft already.