Is that Thread Colorfast?

Updated June 19, 2018
Marlene asked in response to a post how to tell if threads were colorfast. Like most stitchers I have had a few unpleasant experiences with colors running. Today we’ll talk about what colorfast means, what kind of threads are less colorfast, what you can do about it, and what to look for in the needlework shop.

What is “colorfast?”

The term “fast” refers to the permanance of the threads color under different conditions. “Lightfast” means the color will fade more slowly when exposed to sunlight. “Colorfast” means the dye won’t run when exposed to water.

The more (and hotter) the water is the more likely a color will be to run. Threads that might not run when blocked with water, might run if put through the dishwasher. This happened to me with Watercolours stitched and inside a supposedly waterproof mug.

If threads will be exposed to wet conditions, you need to be extra sure every color of every thread is colorfast.

Less Colorfast Threads

Since there are new laws about pollution, many dyes that were more fast can no longer be used. This makes some colors, particularly reds, more likely to run.

More dye is used when dyeing darker colors than lighter ones. The more dye In these cases, it is likely that there is excess dye, so darker colors are more likely to run than lighter colors.

Finally, and I’ve learned this from experience, hand-dyed threads are often much less colorfast than threads from larger companies. Some lines are pretty good, some lines are not colorfast at all. Experience will help you tell.

Many companies will tell you on the label or on their website if their threads are colorfast. If you don’t know test.

If you do not know and cannot test, assume the thread is not colorfast.

Making Threads More Colorfast

There are two methods you can use at home to make your threads more colorfast. Sometimes one works, sometimes the other.

Vinegar is a great and inexpensive fixative. Make a bath with one part white vinegar to three parts water. Let the thread soak for awhile and then rinse thoroughly.

Many dyers do this to their threads. It doesn’t hurt the threads and fixes almost all dyes.

For threads that have excess dye solution in them, try rinsing them under cool running water. If they are a washable fiber, you could also wash them with baby shampoo. Rinse until the water is clear.

Only do this with threads where you are pretty sure there is excess dye. If the color gets lighter, excess dye isn’t the problem — you need to do the vinegar treatment.

Finally there are commercial products made for fixing colors, but I haven’t tried any of them, so I can’t make recommendations.

What to Look For in your LNS

When you look for threads in your LNS, look on the label to see if the manufacturer says anything about colorfastness or washability. If a thread can be hand-washed, it is probably colorfast in cool water (but probably not in hot or exposed for a long time). Even if the label says the thread is washable, it probably only applies to cold water, unless it specifically says washable in hot (or warm) water.

Some companies say their thread is colorfast. Even so, I’d be cautious of reds and dark colors.

Some companies, mostly those making hand-dyed threads, say their threads are not colorfast. Believe them; it’s always better to err on the side of caution.

If the thread you are buying says nothing on the label, assume it is NOT colorfast if:

it is hand-dyed
it is red
it is a dark color
it is dyed using natural dyes, many of which are less fast.

When in doubt, test and treat. If it still runs, don’t use the thread or dry block. When you have items finished, specify dry blocking. There are finishers who will wet block everything unless expressly told to use dry blocking.

If you really, really need a colorfast thread that has to stand up to water, consider using a washable knitting yarn; they are made to be colorfast.