Until very recently, I thought the usefulness of fabric starch was limited to my husband's shirt ironing - he learned to iron shirts 'correctly' in the army, and boy was it drilled in well - not something I needed in my sewing room. Oh how wrong I was!
Digitizing classes taught me this trick (as well as many others). Before you embroider - starch & iron your fabric - it holds up better, hoops more easily & helps prevent puckering.
Working with delicate fabric in appliqué? Starch & iron it first, it will be easier to handle!
Soft, static fabric - spray some starch on - it helps! Yesterday I was working with shot taffeta - which is always very static, but in our dry Berlin winter, it is a nightmare! - and a quick spray of starch helped this too!
Working with satin bias tape - starch makes it easier to handle.
Silky, slippery fabrics: simply spray a little on, even if you don't iron & rather leave to dry, makes it easier to control while sewing. Helps prevent rolling edges of stretch cotton while working & you can wash it out after.
Here is the starch I use:
I mix it in the spray bottle (one tiny pour of starch filled to top with distilled water) and apply generously to fabric before ironing.
This type of starch is ACTUALLY meant to be added to the washing machine, but it works very well this way too. Also, it smells heavenly!
A few things:
1. Shake bottle & spray bottle very well before each use
2. Spray on reverse of fabric
3. Test on small piece of extra fabric 1st - just in case
4. Make sure iron is on correct setting for the fabric you are using