Double mounts, my brain vs the GCF

[girlfromkent]

Hello

When cutting double mounts, my usual method is to cut the top piece to the glass size, then the underneath piece to 4mm smaller. I cut the first window, retaining the fallout, stick the underneath piece to the top, then cut the second window.

This means the window margins are always even, because the outside edge of the mountboard touching the rule is the same both times. It works fine for me.

However, looking forward to taking my GCF, I was recently told this is frowned upon, and that the pieces should be solid with no overlap at the edge. Well, I like doing things properly so I'm fine with changing my ways. But can someone tell me the usual way to go about this? Do you cut the whole thing, say, 1cm bigger than glass and then cut it down? I think my brain may be misfiring here...

Thanks,
Megan

[pramsay13]

I do it the same way as you've described, albeit 5mm smaller. That's the way I was taught and that's the way I'll continue to do things.
I guess the only downside of doing it this way is that if the glue fails the bottom mount could slip down, but that has never happened for me in almost 15 years of framing.
The downside of cutting the pieces the same size as you say is that it's possible for there to be slight differences in margin widths, probably more so with a manual cutter rather than a computerised one.

[JKX]

This is what the GCF study guide says but for CMCs it should say “can be” not “are”, well actually it should be can be for manual
mount cutters too!

It’s whatever works for you and I don’t think the guild would frown on either way as long as the two layers are fixed well
and the reveal is equal all round.

[Tudor Rose]

As a GCF Examiner either way won’t be a problem. Whichever version you prefer. As long as the measurements and reveal are accurate and the double mount is well cut, and glued together properly, then it’s totally fine.

I don’t know who told you otherwise but they may have misinterpreted things.

[girlfromkent]

Ah OK, that's a relief. Thanks both for the clarification.

My brain rests.

[prospero]

I've always done it the way you describe. It's the elegant solution.

Trying to align two windows perfectly on two pieces is very tricky and a lot of extra work and stress.
For a start you have to cut the layers exactly the same size and keep the two in the same orientation.
No matter how you try there will be slight variations.
Why struggle when there is a much better way?

[IFGL]

I have been using a CMC for so long I can't remember how we did it before we had one.
Hope this helps!