large canvas for stretching

[GeoSpectrum]

A large canvas came in today (rolled up, all the way from Sri Lanka). It is 7ft x4 ft and needs stretching. The owner removed the frame when bought so he could get it home and I'm quite looking forward to the challenge.

I'm plannig on constructing the frame using pine, possibly 70mm x 25mm with 1/4 rounds for the edges. obviously some cross bracing and corner bracing using sheet mdf, but I'm worried that it might warp over time. Is there another wood that I should consider? Or a better construction?

With a L profile from wessex round the edge, (PW142) (need to check the depth) the whole thing is coming out at £382. Am I way over the top or am I just not used to this size frame?

Thanks

[Graysalchemy]

I use the two way profile with 2 x 1 " cross braces going both ways which I biscuit joint together. Obviously with this method the joints will be fixed but I find on this sort of work it is fine. However you do need to stretch very tight. I have just completed one 3m x 1.5m as well as a load 1m x 1.5 all made using this method.

Mainlines do two 2 way profiles the thicker 300-2140would be better and is quite inexpensive at about £1.60 a metre for the so you should be able to make a good markup on it.

Cheers

Alistair

[GeoSpectrum]

Thanks Alistair,

What about wedges to retension the canvas? I'm concernered about the canvas 'relaxing'.

[Graysalchemy]

I have stretched thousands of large canvases using fixed joints and never had a problem. The trick is to stretch really tight.

[prospero]

It depends on the quality of the canvas. The 'canvas' on some of these holiday things can be quite iffy. So can the paint.

If the customer wants to keep the costs down, then an simple stretcher frame with no keyed corners is OK up to a point. It might go on nicely and stay flat...... I've known top quality canvas on expensive paintings go floppy in the right (or wrong) situation.

But it would make life easier if you had a proper keyed frame. It's a big area to manage and pulling staples out to readjust takes an age. You have keyed corners you need only get the thing reasonably tight. If you do get a wave, you can apply tension more delicately and with more control by tapping in the appropriate key. Best to do it gradually. Bit of tension - leave to relax - bit more.....

The term 'stretching' is misleading. The aim is to get the surface flat and not flapping about. The less stretching the better.

These folks do some good stuff. Get a good hefty bar and don't skimp on the cross-braces.

[Gesso&Bole]

Often a 'canvas' is nothing of the sort, and if you are saying Sri Lanka, it may well be quite thin cotton type material and very delicate if you pull it too hard with the stretching pliers.

I'd go with the fixed frame (cheaper, exact size, less likely to flex), and not stress about getting it 'drum-tight'.

[Jonny2morsos]

I am always wary of these sorts of things because as Jim says they are often not canvas at all and I have had a few come in that are on material looking like bedsheets!

I would rather turn the job down than rip the material.

For large jobs I like the Lion Premium stretcher bars with cross braces.