WhatFabric

What is it made of?

(Part Two).

Fabric tests.

Editor. Brian Lemin

Introduction.

In order to add this to the original article on "What is it made from?" I have culled and combined the information from two published sources and also a technical contribution from Luigi (and advice from his wife) The two articles were sent to me by, Tammy ………..

Many thanks to all involved.

Which Test?

I can not emphasise enough the need to avoid destructive testing, therefore visual and feeling, testing skills should first be developed by those wishing to identify fabrics.

Of course, we should always try to identify the fabric with a non-destructive test first. So I will deal with the "Look and Feel Test" first, then the "Break Test" and finally the "Burn Test." What follows is a technical comment by Luigi.

Look and Feel Testing.

Cotton: It is soft, inelastic and cool to the touch. If you visually examine it, it is dull to look at and has short soft fibres.

Linen: This has a leathery (stiffer) feel about it. Visually it has longer (than cotton) fibres and is more lustrous.

To differentiate further between Cotton and Linen, pull a thread through your tight finger and thumb. The cotton is limp and the linen has some stiffness with it. Cotton tears easier than linen and linen is believed to absorb a drop of saline quicker than a cotton fabric.

Examine a linen handkerchief, it can be creased easily.

In ancient laces (18th Century), the most used thread was linen, because cotton was too "woolly" and opaque. Only in the 19th Century the introduction of a new way of working the fibre (in Italian is called "mercerizzazione" [presumably "mercerised" in English]- immersion in caustic soda) allowed the use of cotton for artistic laces.

Wool: Warm, springy, and elastic to touch. Visually it has short soft fibres.

Silk: Soft, smooth (almost shiny smooth) and warm to touch. It is somewhat elastic. Visually it looks somewhat lustrous.

In earliest Chantilly laces was used a silk called "grenadine"; tightly twisted, it was less bright than normal silk, resembling linen. The colours used were ivory and black.

Rayon: Has a cool feeling, inelastic, but smooth. Does not have the "quality" feel like silk does.

Break Testing:

Before you break test a fibre you will need to untwist about a foot of it, so that it resembles its unspun state.

Cotton: It breaks with a snap. But look at the broken ends; they are very fuzzy short fibres. (You know how difficult it is to thread needle with a broken cotton end as opposed to a cut end) There will be evidence of the curl of the twist too.

Linen: Has more resistance to breaking than cotton. The broken ends are more straight than cotton and the lusterousness can be seen.

Wool: Stretches quite a bit before it breaks. The ends are wavy and Wrigley.

Silk: Stretches before breaking, then breaks with a snap. The broken ends are quite fine and wispy.

Rayon: Really quite strong and inelastic. Almost have to break it not by pressure but with a jerk. If you moisten it with your tongue then it breaks more easily.

The Burn Tests

Please remember that this is potentially dangerous. (Like ending up with your house on fire and all your lace projects and bobbins gone up in smoke!) Remember too that your kids may be watching and they LOVE to copy you. I do not want to appear stupid about this but fires really do happen and they can sometimes happen to you. So please, please, please, do not take short cuts with your safety.

The key descriptors in these tests are shrink, curl, and melt. The differentiation is shrink away from the flame or does not shrink away from the flame. Smell also comes into it.

Before we start the specific reactions of fibres to flame, I offer the following basic review of the three main groups of fibres.

Vegetal fibres (cellulose): e.g. linen, cotton and rayon: they burn

Animal fibres: (cheratine, and other animal proteins): they don't burn easily

Artificial fibres: they burn or mainly melt

So here we go. Use a match and slowly bring a few unravelled threads of the fabric into the flame and see what happens.

Cotton and Linen: Does not shrink away from the flame. Burns with a yellow flame. Burns well, even quickly. (blazes?) Still burns after you have taken it from the flame. The smell is like burning paper. There are two types of ash that you may see fluffy and grey or fluffy and black (That shows it is mercerised) Linen could be said to burn slower than cotton if you are able to judge that.

Wool: Curls away from the flame. Slow to start burning and burns slowly. The flame flickers, the wool melts a bit and sort of sizzles. It almost stops burning immediately when the flame is withdrawn. The smell is said to resemble burning feathers or burning hair and the ash is lumpy and brittle, quite crushable.

Silk: Pure silk curls away from the flame. Burns slowly and stops burning when withdrawn from the flame. There is some melting. Smell is said to be of burning feathers. Filled / weighted silk hardly burns with a flame, It sort of glows and smoulders. The ash forms a brittle, black crushable bead. If a piece of silk is burned as opposed to some threads, then a skeleton of the fabric is left after burning.

Rayon: Does not shrink from the flame. Burns sprightly and with a yellow flame. It continues to burn after being removed from the flame. Very little ash. Smells like burning wood.

Acetate: Melts away from the flame. It seems to combine blazing with melting as the flame consumes it. The smell is of vinegar. The ash is a brittle irregular blackish bead.

Polyester and Nylon: Shrinks away from the flame and fuses. Burns slowly with very little or no flame. Ceases to burn when the flame is removed. The ash distinguishes between polyester and nylon. The polyester ash is round hard black beads and has a chemical smell. The nylon ash is also hard round beads but they are gray and are said to smell like "boiling string beans!"

Acrylic: Fuses away from the flame. Burns and melts rapidly this continues after the flame is removed. The ash smell is acrid and is a brittle black irregular bead.

Microscopic examination

High magnification microscope (100 - 600 x). The fibre must be prepared untwisting threads, with an apposite needle, and the elementary fibres must be isolated.

You must prepare a solution of 10 ml of distilled water and 1 ml of glycerol.

A little tuft of the tissue must be posed on a glass slide, then a drop of the water solution and then a cover slide.

Vision under the Microscope:

Cotton: a plain and spiralled tape. A central channel can be seen.

Linen: the fibres are cylindrical with regular enlargements: they resemble bamboo.

Wool: the fibres are cylindrical and fully covered with little scales (like a tile roof).

Silk: raw silk: a double band (kept together by a protein called "sericin"; worked silk (in Italian "seta cotta"): a single band, very regular and bright.

Rayon and all other artificial fibres: they are extremely regular; the shape and diameter of the section depends on the wire gauge

NOTE

Some ancient laces have also metallic threads (generally gold)

Chemical test

The only simple test is based on the solubility of Rayon in acetone. Other tests are more complex, expensive and require special instrumentation.

Conclusion

It is a pity to think that most of the fabric that we want to identify is very old or antique. The look and feel tools must be emphasised and developed by would be testers. The somewhat lesser destructive test, the break test will also give valuable clues. So, do try those methods before you start burning potentially valuable fabrics.

References.

Terreni V., Amandola G.; Merceologia 2000; Masson; Milano; 1988; page 467-501; ISBN 88.214.0482X

The Identification of Fabrics is from the

book Antique Children's Fashions 1880-1900, A Handbook for Doll Costumers by

Hazel Ulseth & Helen Shannon. ISBN 0-87588-192-0, published by Hobby House

Press, Inc. Cumberland, Maryland 21502, 3rd printing 1985. It is a cool book

:-)

The Burn Test is from a book called All About Cotton, A Fabric dictionary &

Swatchbook, written & illustrated By Julie Parker (ISBN 0-9637612-1-8 the

of a set; the other book is All About Silk, rest is the same as above (ISBN

and my book is Second Printing 1994.). These books are from Rain City

Publishing, 7501 43rd Ave, NE, Seattle, WA 98115-5107.