What does 6A silk mean? How to check a grade claim

6A is the top grade for raw silk yarn under China's grading standard. It tells you about the yarn before it is woven, and nothing about the pillowcase made from it. You will see 6A on plenty of silk listings, so it helps to know what it covers, what it leaves out and how to check it.

What does 6A mean on silk?

Raw silk is graded under a Chinese national standard, GB/T 1797-2008. The yarn goes through tests for size deviation, evenness, cleanness and neatness, and the grade is set by the lowest score.

That last part is the useful bit. A grade is not an average. One weak result sets the grade, however well the yarn did on the others.

6A is the top grade on that scale. Trade sources describe the scale running from 6A down to F. We have read a published paper on how the grading works, not the standard's own text, so take the detail of the scale as the trade's description.

Is there a 7A silk?

No. There is no 7A or higher grade. 6A is the top of the scale, so a higher number on a listing is not a grade you can look up. If you see one, it is fair to ask what it is based on.

Does 6A tell you about the finished pillowcase?

No. The grade rates the raw yarn, not the pillowcase. Raw silk still carries sericin, the gum that holds the strands together, and that is washed out in degumming before smooth fabric is woven. Plenty is decided after the yarn is graded, and the grade covers none of it:

• The weight. Momme measures how much silk is in the fabric. 1 momme is 4.34 g per square metre, so 22 momme is about 95.5 g/m². Higher momme means a denser fabric. It is not a grade of quality. Our guide to what momme means has more.
• The weave. Charmeuse is a satin weave with long floats on the face, for a glossy surface and a dull back. It can be woven from silk, polyester or rayon, so the word alone does not mean silk. Our post on silk and satin explains why that matters.
• Testing for harmful substances. OEKO-TEX Standard 100 is a separate label, for textiles tested for harmful substances. A yarn grade says nothing about it.

Grade also sits apart from the word mulberry. Mulberry silk comes from silkworms fed on mulberry leaves, and our guide to what mulberry silk is explains how it is reeled. A listing can use both words, and each one is a separate claim.

Is 6A silk better for hair or skin?

No study shows that. There is no peer-reviewed study of a mulberry silk pillowcase on hair, wrinkles, acne or skin moisture, at any grade. The same goes for weight: no study shows a particular momme gives better hair or skin results.

So a grade is a fact about yarn, and it stops there. If a listing ties 6A to what will happen to your hair or skin, it is fair to ask what that is based on. The short version on our science page grades every claim we looked at, with the sources listed.

How do you check a 6A silk claim?

Ask for the raw silk inspection certificate. A sales sheet that says 6A is a statement, not proof. The certificate is the document that shows the grade.

The same habit works for the rest of a silk listing. Each claim has its own document, and a seller can tell you which ones they hold:

• Grade. The raw silk inspection certificate.
• Momme. A fabric mass test, which measures mass per unit area under ISO 3801.
• OEKO-TEX. A certificate number. Certificates last one year and can be checked by number on the OEKO-TEX Label Check.

Asking is reasonable. UK advertising rules say a business must hold documentary evidence for a claim before it makes it, so a seller who prints a grade should have something behind it.

Our science page covers momme, grade and OEKO-TEX in a few lines each, and the FAQ answers the common questions about the silk itself.

What does SOIEA say about grade?

We hold ourselves to the same test. A grade should come with its certificate, so SOIEA will state one only when the supplier documents prove it.

SOIEA is 100% mulberry silk at 22 momme, in champagne and blush, launching in December 2026 for the UK and Ireland. It is smooth and soft against your skin. Choose it because you love how it feels. See the pillowcase.