Linen vs cotton for large scale

​Hi
We have recruited a textile conservator to comment on this question. Please check back in a day or so. Thanks

Most commercial cotton canvas offered today are actually blends of cotton and polyester fibers. Some cotton canvas we have studied consisted of as much as 65% polyester in both the warp and fill weaves.

It is generally recommended to use 320 g (~10 oz) unprimed linen canvas and 320 to 400 g (10 to 12 oz) cotton canvas for pictures larger than 120 cm (48 inches). Cotton and polyester canvas has strength closer to that of linen.
Light-weight: 140 to 170 g (4 to 5 oz)
Medium-weight: 240 to 270 g (7 to 8 oz)
Heavy-weight: 320 to 400 g (10 to 12 oz)

​I was uneasy about the statement that most commercial artists’ canvases were composed of blended fibers but refrained from commenting until I heard from someone in the industry. I received this comment today and am posting it for them. Their response is in black.

The majority of commercially available artist canvas is not PolyCotton.   
https://www.artcons.udel.edu/mitra/forums/question?QID=341
Artist Canvas is available in three distinct categories:
1) Linen – this is fabric that comes from the fibers of the Flax plant. It is very sturdy and durable. (warning – much of the canvas from Asia that is referred to as linen is a 100% cotton fabric that has been dyed to look like linen)
2) Polyester and/or PolyCotton blends – synthetic fabrics or synthetic blends. This is especially prevalent in student grade canvas panels and works great for smaller stretched canvas.
3) 100% Cotton – The majority of Artist Grade Canvas is 100% cotton. A great example of 100% Cotton Artist Canvas is the Fredrix Pro Dixie or the Fredrix Red Label Cotton Canvas.
We’d be happy to send samples to your industry expert if you’d like.
Best wishes,
Paul Straquadine
VP Sales Tara Materials/Fredrix Artist Canvas
322  Industrial Park Dr
Lawrenceville, GA 30046

​To the original poster: It seems that the jury is still out regarding your specific question. What I would state is that cotton fibers in general are much shorter than flax (linen)…this can certainly contribute to potential deformation later on down the road. Speaking from personal experience I tend to see more planar deformations occur in cotton duct canvases than in linen but more research needs to be done in order confirm my observations. All in all such deformations can be readily dealt with by conservators….I would just ask that you consider using a stretcher with expandable corners or even stretching your large format canvas over a rigid support (backing boards are also good). Hope that is of some use.