Need help with matte center with window gold leaf.

If you are talking gold leaf I believe that you just use a different size. A low tack tape for what? A mask for the size?

 

If necessary, outline & shade in black first.

Matte centres?
I just brush them in freehand, in size (oil-based, like varnish).


Then gild (watersize, with gelatine).

Then back up with a strong black.

(then clean up any edges with a razor, if you hadn't outlined it first, which you should have, to make it easier.)

I have never used any tape-low tac or otherwise, on the grounds it may contaminate the glass & impair the adhesion for the watersize & gold.

If you have done several burnished gold jobs before, then just experiment a bit, yourself...

 

I know jack all about leaf but I seem to remember hearing about old timers putting a drop of yellow into the oil size so that it became just visible but didn't show on the gold. Take this with a grain of salt, let someone in the know confirm.

 

Tebond...

how about some proper sentences with full stops or periods after them, please?

You're asking for technical advice, yet you're explaining yourself in one long ramble. I don't know where to start, so I won't bother, but I'll go back to the earlier reply I gave you which is still good advice:

Just experiment YOURSELF - give it a try-you'll only use up 2 or 3 leaves of gold and that's cheap tuition. Make up a letter, like the T of tebond, and try three different ways of doing a matte centre, if you wish.
There is NO better way to get that answer you want.

I suggested what I would do, and that is what I would do- paint the outline & shade in black, first, then brush in the matte centres with a clear varnish or oil-based goldsize, then when totally dry, use a gelatine watersize and gild over the top of everything at the same time, with loose leaf gold.

The only time I'd do the centres with a transfer gold leaf, or in a separate gilding stage would be if I wanted them in a pale lemon colour, like 16 ct or 14 ct gold- but then you're getting the different looking effect with the matte centre of 24 ct anyway, so why make it all take longer & do double the gilding when you don't have to? Why worry about 'discolouring' when it's going to be a different looking colour anyway due to the matte centre? I just use clear size/varnish -you can see that readily enough anyway as you brush it. Tint it a whisker if you have to-it's up to you. If you're worried about it looking different then why are you having the matte centre anyway?

If you have experience with gilding, as you say you have, then I recommend you experiment and answer your own questions, then report back here with your conclusions, please! The reply might then be useful to others...

P.S. No offense intended with any apparent abruptness you might read into this- but it really is up to you to figure it out.
The Yankees gild in a different order from the Poms, and different from the Aussies, but there's some overlapping in places.
I think our way is the simplest: just do it!