Give preference to yarn, originally created and intended for children's products - this yarn with special marks shall, on the production of more thorough quality control and safety for kids.
If a particular yarn has not been found, consider the following guidelines. Stop your choice on the yarn of natural fibers - cotton, wool or at least acrylic. Natural yarns allow legs of a child to breathe, absorb moisture, at the same time keeping a constant warm booties will not be electrified, creating a charge of static electricity. The only booties knitted from natural yarns can after the first wash slightly reduced in size, so either you need to pre-link the sample and wash it to look at the shrinkage of the product, or to knit booties and little more than a baby's leg - in any case, the baby grows rapidly and even a little large booties soon he will be useful.
Yarn does not have to be painted bright vivid colors, because, most likely, particles such as paint, will stand out, affecting not the nicest way to sensitive baby skin. However, one should not fall into the other extreme and make shoes for baby white - there are a lot of muted, pastel tones.As for the child, child psychologists found that at a very early age the kids love the shades of yellow, green and orange. So the yarn can be selected and based on the preferences of the baby.
But the thickness of the yarn does not matter - except that booties for the cold period tally from thicker, and in summer, when the street and the house is so warm on the legs can wear a light hat and a thin thread. Although, of course, children at an earlier age is better to choose a thin and soft yarnthat would not be rubbed the sensitive skin.
And finally, get the yarn tested brands and well-known manufacturers, so the threads are not rolled out and not deformed, with the love associated booties not lost their form after couple of days wearing and washing.