Cracked Slips ...

[Bagpuss]

Hi,
I haven't used slips much in the past so any advice would really be appreciated.
As you can see in the photo below, when I place the canvas board in the back of the frame and slip, a couple of the corners on the slip
have gaped open Now I had stuck AND underpinned the white slp (16mm wide). Would you send this out to the customer ?
I'm not happy with it, it's happened on a couple of identical frames. The slip is stuck down into the frame using fillet tape, then I lay
pH7-70 tape over the face of the slip that comes into contact with the canvas board.

Should I just take it apart and try again ? Any tips ?
Thanks in advance,
Bagpuss

crack appears in corner of white slip

big_crack2.jpg (23.47 KiB) Viewed 2604 times

[markw]

Those little clear lipstick things work...... Oh no - that's cracked lips, sorry!

[markw]

suppose I ought to try an intelligent reply: couple of thoughts spring to mind. Slip has slight warp and its not cutting well. would think you would notice that so unlikely. Rebate of main moulding has been machined with a slight slope - or the finish creates a slight lip - both could open the corner.

A solution would be to join the slip before assembly - making sure the joints are well glued and allowed time to set. I have 3mm wedges on my underpinner and can often get very good joints in a slip.

[Spit]

Are the slips too tight against the corners/aperture of the frame? Could be bowing out slightly due to pressure.

[prospero]

This is going to be hard without drawing diagrams, but...........

Is the edge of the canvas board perching on the edge of the slip, or does it go right up to the edge of the outer frame?

If the former case, the canvas board will be applying pressure to the sight edge and levering it up, causing torsion on the corners. There is a limit to just how strong you can make a corner join on a slip, so you have to make sure there is no strain on them. One way I use is to lock the slip in place with a piece of strip wood, tacked to the inside of the outer frame rebate.

[Bagpuss]

Thanks for getting back to me everyone, Prospero was spot on, there was about a 1cm gap between the edge of the frame and the canvas board. When I attached a backing board and tried to secure it at the back, I was putting too much stress on the slip. I was able to put a bigger backing board on the back and then attach direct to the back of the framer, that seems to have done the trick.

Thanks,
Adam (B'Puss)

[Spit]

I was able to put a bigger backing board on the back and then attach direct to the back of the framer

So you're now walking around with a picture on your back?

[Bagpuss]

doh !!