I've been using starch for my piecing and quilting for years, and I make my own. The only drawback is the lack of preservatives, so it's necessary to build a new batch every week or 10 days if you refrigerate it, and dump out what remains.
Why do I like starch? What is the recipe I use?
When I started piecing quilts ages ago I realized that fabric has a life of its own. It stretches, it frays, it distorts during any piecing or quilting process.
Because I wash or rinse thoroughly every quilted piece when it is finished I knew it was ok to add starch for the process, as it would be removed when the quilt was completed. If you don't wash the quilt when done, you probably don't want to add starch or wash-out markers or anything that should not be left in the quilt for long periods.
However, my biggest issues were getting long border strips to stay the same measurement before cutting, after piecing, after pressing, and starch was the key.
I wash, dry and press all fabrics with a light misting of my starch mixture before measuring and cutting for the project, not long-term storage.
Sometimes I add a mist of starch for piecing as I progress, but most times a gentle mist of water is enough to re-activate any starch in the fabrics.
For a block like log cabin I really add quite a bit of starch so those logs don't stretch and distort as I piece them around the center square. I don't do foundation piecing, so control of the fabric is key.
I also like to wash and dry the backing fabric for a quilt, and then press it with a misting of starch to stabilize it, to help prevent it from puckering and pleating, and to help it slide easily on the machine bed. Starch makes a huge difference for successful machine quilting in a home machine.
For small triangles, e.g. in a feathered star block, starch really helps in keeping them stable and even. I do starch before cutting them, and always be careful pressing damp fabrics as they can distort in a blink of an eye.
Even if you starch pieced parts of the quilt heaviliy or repeatedly, as you quilt the fabric softens and is easy to deal with in the sewing machine.
What is my recipe? Remember, you can adjust the amount of starch added to water to get exactly the consistency you need for any given job.
I like to begin with a thicker concentration, then dilute it as I go along in the piecing. Or start with what I recommend and check out how it works for you, then make a thicker batch or dilute this one until it is "just right," like Goldilocks.
If you have made sauces or gravies, Jello, the technique is the same.
I begin with a scant teaspoon of Argo cornstarch (or whatever brand you have, but the kind of cornstarch for cooking, not laundry), dissolved well in a few tablespoons of cold water, in a heat proof 2-cup measuring pitcher.
Add boiling water to the 1-cup line, stir mixture until it turns transluscent.
Then add cold water to the 2-cup line.
Pour into a fine-mist pump sprayer. I get mine from the beauty section at the drugstore and the mist is very fine, not drippy or gloppy.
Label it so you don't think it is water.
Shake it every time you spray.
If you spritz the fabric and press carefully parallel to the selvages of the fabric it will give it a wonderful body. Don't push and pull on the fabric with the iron; be gentle, let the weight and heat of the iron do the work for you.
If white flakes develop as you press, you have too much starch or the mix is too concentrated. Either use less, or dilute the mixture.
Lasts a week or so as there are no preservatives, no chemicals, no nothing that harms us or the environment, and it’s practically free, except for the spray bottle! Don't starch fabrics for storage as I have heard it will attract critters such as centipedes, and mice. Use sparingly at first. You want the quilt to feel soft and be able to gather it up in your hands for quilting.
Hope you enjoy the starch, and if you come from the "no ironing" generation it will be a delightful surprise.
There are new commercial formulations of starch on the market, so give those a try too until you find what works best for you.
Keep quilting! Your work gets better every day.