Name: Tiffany 

Message: I have a couple of pairs of shorts and paints for my sons school that I hemmed and have a crease now with a discolored line. I am wanting to dye redye it a Navy it is 65% polyester and 35% Cotton. I was looking at your polyester issues and how it is hard to do, if it is 35% cotton will it adhere to the fabric better? And what kind should I get? 

I'm afraid I have bad news for you. If you dye a 35% cotton/65% polyester pair of shorts with cotton dyes, you will get a color that is only 35% as dark as you want, since the polyester in the blend will not take the dye.

You can dye both fibers in a poly/cotton blend at once by mixing Jacquard Products' "iDye" dye for cotton with their "iDye Poly" dye for polyester and boiling the shorts for some time. You can mail-order iDye and iDye Poly from Dharma Trading Company and other retailers for Jacquard Products.

However, to use these hot-water dyes, you must invest in a dyeing pot, preferably five gallons or more in size. Your dyeing pot must be made either of stainless steel or of unchipped enamel, not aluminum or iron, and you must never reuse this pot for food preparation, once you've used it for dyeing clothing. I believe that you could buy several new pairs of shorts for your son for the money that this dyeing pot will cost you. It's a good idea only if you plan to use your pot for dyeing clothing again in the future.

If the goal is simply to save money, then dyeing a cotton/polyester blend is not going to do it for you. It is very easy to dye 100% cotton shorts at room temperature, using Procion MX dyes, which don't have to be cooked, so the equipment needed is inexpensive, but dyeing polyester requires a dyepot, which can be expensive.

On the other hand, it might be that you could cover up the line from the hem by getting fabric crayons, which contain disperse dye and work only on synthetic fibers such as polyester. You can find these at the sewing store. To use them, color a solid region on paper, then place this face-down on the line on the shorts and, using a hot dry iron, iron it on. The polyester dye transfers with the heat of the iron. (Be sure to put a good many layers of newspaper on your ironing board to protect it.) The results will not be perfect, but they might be less glaring than the faded line you have now, and the expense of a box of fabric crayons is not very large. Be sure that you do not confuse fabric crayons with regular crayons: they look almost identical, but they cannot be substituted for each other at all.

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