Home /
Search 🔍
the Site
pub Where the world gathers for
plating, anodizing, & finishing Q&As since 1989


Swedish Standard St2 / St3

May 1, 2022

Q. Good morning sir, can you kindly tell me what's the meaning of Sa. 2.5 & St 2.5 standard? For building works, how can we use sand blasting.

wing tat kwok
technical director - china hong kong

May 2022

A. Hi Wing. Sa 2.5 is a surface finishing standard for sand blasting. Apparently the standards range from Sa 1 (roughest) to Sa 3 (smoothest), with Sa 2.5 being a bit shy of Sa 3. Thread 12526 goes into a lot of detail about these sand blasting standards.

The St standards are apparently for cleaning up surfaces with hand or power tools rather than blasting. There is an St 2 standard and an St 3 standard, but I am not sure that St 2.5 even exists -- there may be a quantum jump from Sa 2 to Sa 3; please see

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Closely related Q&A's, oldest first:


Please advise what Swedish Standard St2, St 2 1/2 and St 3 mean in finishing surface. Our company is involved in some corrosion protection work here in Taiwan. Recently, we have search for some products which require a surface finishing standard in accordance with St 2 or 2.5. We like to know more about the standard and related information. Please be kindly to advise. Look forward to hearing from you. Regards, Many thanks.

Viktor Yue
Painter - Taiwan


These are specific ratings of surface finish/cleanliness within standard SIS 055900, which is apparently now ISO 8501. Suppliers of paint testing instruments can sell you binders which include the standard and examples of such finishes, or you can obtain the standard from ISO. It's pricey.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

Chemicals &
Consult'g, Train'g
& Software

About/Contact    -    Privacy Policy    -    ©1995-2023 finishing.com, Pine Beach, New Jersey, USA