Name: Daniel
Message: While I see how both cotton and polyester are to be dyed, what do you do in the case of an article being 65% polyester and 35% cotton?

You have two choices: either you choose to dye just one of the two fibers, leaving the other undyed, or you dye the two fibers with two different dyes.

There is no cotton dye that will permanently color polyester, and there is no polyester dye that will permanently dye cotton.

If you use a cotton dye, such as fiber reactive dye or direct dye, you will get a pale or muted shade, since only 35% of the fiber will accept the dye. If you dye only the polyester, using disperse dye and the appropriate carrier chemical, you will get a more acceptable final color; omitting the carrier chemical will result in a paler shade.

If you choose a high quality fiber reactive dye, it must  be applied in a separate dyebath from the polyester dye. Fiber reactive dye uses much lower reaction temperatures and different chemical auxiliaries.

If you would prefer to use both dyes in a single dyebath, dyeing the polyester boiling your garment for an hour with disperse dye and the appropriate carrier chemical, you will probably be able to also apply direct dye in the same step. However, this does not really save trouble, since direct dye requires an addition dye fixative treatment, after dyeing has been completed. Direct dye is not acceptably washfast, so you must apply a cationic dye fixative after dyeing has been completed.

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