ASTM B700
Standard Specification for Electrodeposited Coatings of Silver for Engineering Use
Specifies electrodeposited engineering silver by purity, appearance, supplementary tarnish treatment, and purchaser-defined thickness.
What ASTM B700 specifies
ASTM B700 covers engineering silver for electrical and thermal conductivity, solderability, thermocompression bonding, wear surfaces, and reflectivity. Type 1, 2, and 3 require at least 99.9%, 99.0%, and 98.0% silver. Grades A, B, C, and D identify matte, bath-bright, polished bright, and semibright appearance. Class N has no tarnish treatment, Class S uses chromate, and Class T uses a non-chromate tarnish-resistant treatment. Thickness is not fixed by those classifications and must be stated by the buyer. Underplates, significant surfaces, hardness, solderability, conductivity, and embrittlement controls should also be specified.
ASTM B700 types and classes
Every designation the document defines, with the thickness it requires and the tests it imposes.
| Designation | Meaning | Requirement / test |
|---|---|---|
Types 1–3 | Minimum silver purity 99.9%, 99.0%, and 98.0%, respectively. | Silver purity. |
Grades A–D | A matte, B bath-bright, C polished bright, D semibright. | Visual appearance. |
Class N | No supplementary tarnish-resistant treatment. | Appearance and agreed performance. |
Class S | Chromate tarnish-resistant treatment; not suitable for food service. | Tarnish treatment and agreed performance. |
Class T | Non-chromate tarnish-resistant treatment. | Tarnish treatment and agreed performance. |
Tests and the drawing call-out
Tests the document imposes
- Silver purity
- Thickness
- Adhesion
- Solderability when specified
- Hardness, reflectance, or conductivity when specified
- Hydrogen-embrittlement relief for susceptible steel
How to cite it
Drawing call-out
SILVER PLATE PER ASTM B700, TYPE <1|2|3>, GRADE <A|B|C|D>, CLASS <N|S|T>, <THICKNESS>, UNDERPLATE <SYSTEM>Angle brackets mark the choices the drawing must make; every finish page shows a completed example.
Finishes specified to ASTM B700
ASTM B700 — frequently asked
Does Class S define silver thickness?
No. It identifies a chromate tarnish treatment. Thickness must be stated separately.
Which class is chrome-free?
Class T is the non-chromate tarnish-resistant option. Class N has no supplementary tarnish treatment.
Which purity is Type 1?
Type 1 requires at least 99.9% silver. Type 2 and Type 3 require at least 99.0% and 98.0%.
ASTM B700 is copyrighted by ASTM International. This page explains the document so a drawing can be read; it does not reproduce the standard. Purchase the current edition from the publisher. Official source ↗