What is fabric testing and why should you bother doing it?
If you are wanting to reduce the risk of problems with your fabrics before you sew them into a quilt then testing your fabric could be the answer. Performing specific tests allows you to learn how a certain fabric will behave and more importantly how you should treat it both when storing, washing and dispalying it.
You would test fabrics to learn about
A higher thread count indicates a higher quality fabric.
Dyes bleeding from fabrics or fabrics fading when we wash them is not as simple as it appears. We need to look into what caused the dye to react this way and it could be a number of things that we can control quite simply.
Cotton fabrics used in quilting can shrink anywhere from 2% to 6%.
I'm sure you have noticed the same printed fabric being sold at your specialty quilting shop is sometimes also being sold at the discount store. I have been tempted many times to buy the cheaper version. Don't!. These two fabrics are as different in quality as their prices suggest.
What happens during the manufacturing process of the fabric is that a fabric design once purchased is then printed onto a variety of different quality cotton fabrics to cater for a varied market. This also concerns the quality of dyes and finishes used. So the old saying 'you get what you buy' is very true in the fabric trade.
To date I have not needed to test any of the fabrics I have bought. I put this down to buying quality cotton fabrics from quilting shops.
I have friends that have had colors bleed into other fabrics in their quilt - sole destroying!! I believe some of them managed to buy a product to add to the water when washing the quilt that helped. I just hope I never have to deal with this problem!
(update September 2017 - it has just happened to a rag quilt I made for my granddaughter - the red ran turning the white to a pale pink!! Ugh!! and the fabric was not the cheap variety either.)
Now don't get me wrong here, I have and sometimes still do buy the occasional cheaper fabric for projects where it doesn't matter eg bib sewing but I try to avoid fabrics with a lot of red in them on these occasions.