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Sand blasting standards: Swedish SA 1, SA 2, SA 2.5, SA 3 vs. NACE and Ra


Q. I need to know the technical details about the following- Surface preparation - Cast Iron part (gratings, used for cooking ranges); the surface needs to be prepared by sand blasting as per Swedish Standard, SA 2.5 or better as per Swedish Standard, SA 3. If it is possible then please inform about the surface finish value (Ra, Rmax) which can be achieved by the above mentioned process.

Please respond as early as possible.

Best Regards,

Souren Pal
steel company - Ahmedabad, Gujarat, India

Q. Dear Mr. Souren Pal,

I am also interested in the relationship between the SA standards SA 1, 2 2.5 and 3 and Ra. An interesting answer on your question which may be of help to me?

Best Regards,

Laure Spriensma - Jirnsum, The Netherlands




A. Mr. Souren Paul , Laure Spriensma, Mr. FADI MUSALLAM,

Surface preparation standards are stipulated by various bodies throughout the world to designate the cleanliness condition of blasted steel, prior to applying a protective coating. The applicable cleanliness standard is usually called for by either the protective coating manufacturer or the owner of the structure to be painted. The most commonly referred to standards are SSPC, NACE, and Swedish Standards. Each standard is divided into four standards of cleanliness, broadly described as follows; brush off, commercial, near white metal, white metal. Whilst each standard may differ slightly in requirements and terminology the following cross reference chart indicates the close approximation of each level of cleanliness for each standard.

A brief description of each of the four levels of cleanliness is as follows:

  • Brush Off - Loose mill scale, loose rust and foreign particles are removed.
  • Commercial - Mill scale, rust and foreign particles are substantially removed and grey metal is visible.
  • Near White Metal - Mill scale, rust and foreign particles are removed to the extent that only traces remain in the form of spots or stripes. The cleaned surface will show varying shades of grey.
  • White Metal - Visible mill scale, rust and foreign particles are entirely removed. The cleaned surface should have a uniform metallic colour but may show varying shades of grey when viewed at different angles.

I hope the above info is useful to you. We are setting up a shipyard and are installing a plate preparation shop.


Bijit Sarkar
shipbuilding - Calcutta, WB, India

Esentials of Surface Preparation

Surface Preparation ISO 8504-2:2000

sidebar2 (2007)

Q. May I know the surface profile difference between SA 2.5 and SA 3 in microns?

Shahaji Doltade - UAE

February 17, 2012

A. Dear Mr. Shahaji Doltade
We know that sa 2.5 & sa3 are cleanliness levels not Roughness levels.

Sohail-Hashmi - Karachi,Pakistan

March 19, 2010

Q. Dear sir,
I want to know about measuring instrument for surface finish SA 2.5. I also want to know about from which size of grit we can achieve surface finish SA 2.5.

Your sincerely


March 19, 2010

A. Hi, Prashant. The above discussions lead me to believe that Sa2.5 is not a "surface finish" but a visual standard for cleanliness and is not related specifically to grit size and surface roughness standards like Ra / Rz, and it cannot be measured with a profilometer. Do you have a copy of ISO 8501-1 handy, with its description of Sa2.5? Thanks.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

May 5, 2010

Q. Thanks for the information that SA 2.5 is not measurable in Ra, but we have seen specifications, such as in containers manufacturing that surface finish to SA 2.5 to achieve 25 to 30 micron finish. Is it correct!

- Kolkata, India
May 5, 2010

A. Hi, S P S. Hopefully someone who is more knowledgeable about this will answer, because I don't see how you can measure things that are covered by Sa 2.5, like discoloration, visible oil, and greyness with a profilometer. Nor can I see how you can reasonably expect a given surface profile from performing operations that comply with a blast cleaning specification that is unconcerned about surface profile, and which apparently permits the use of any blasting material of any size for any amount of time.

However, you can certainly specify both requirements, just as you can specify that you want to buy a car with 5 seats and of red color. The color red is neither included nor precluded by the car having 5 seats.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

November 1, 2008

A. I hope this will clear your queries on Blasting and surface preparation..

grade - BS 7079 SS 05 59 00
description, when viewed with the naked eye

SA 2
thorough blast cleaning:Commercial finish 65% clean
The surface shall be free from visible oil, dirt and grease, from poorly adhering mill scale, rust, paint coatings and foreign matter. Any residual contamination should be firmly adhering.
SA 2.5
very thorough blast cleaning: Near white metal 85% clean
The surface shall be free from visible oil, dirt and grease, from poorly adhering mill scale, rust, paint coatings and foreign matter. The metal has a greyish colour. Any traces of contamination shall be visible only as slight stains in the form of spots or stripes.
SA 3
blast cleaning to pure metal: White metal 100% clean
The surface shall be free from visible oil, dirt and grease, from poorly adhering mill scale, rust, paint coatings and foreign matter. The blasted surface must have a uniform metallic colour.


Following is a table giving a clear indication of the comparative blasting grades applicable to national and international standards:

SSPC steel structures painting council
BS 7079 British standards
SS 05 59 00 Swedish standards
BS 4232
NACE, National Association of Corrosion Engineers

white metal (SP5) SA 3
1st quality
grade 1

near white metal (SP10) SA 2.5
2nd quality
grade 2

commercial finish (SP6) SA 2
3rd quality
grade 3

A Surface mostly covered with adherent mill scale, with little or no rust
B Mill scale has begun to flake, rust has started to form
C Mill scale has rusted away or can be scraped off easily and slight pitting has taken place
D Mill scale has rusted away and general pitting can be seen with naked eye
Sanjay Mungee
- Baroda, Gujarat, India

June 11, 2009

Q. Dear sir
We want photographs of standard blasting profiles like Sa 2, Sa 2.5, Sa, 3 etc.

KIRIT D. PARMAR - coatings - Vadodara, Gujarat, India

August 13, 2009

Q. I want sand blasting profile books for SA2 and 2 1/2 with complete pictures. Please let me know where can I find this.
Thanking you in advance.

Shivaraju Ramarao - contractor - Vizag, AP, India

October 21, 2012

A. Hi Kirit; hi Shivaraju.
HMG Paints Ltd. offers a free 24-page PDF with pictures of these surfaces at:

But I think you'll want to try to get a look at ISO-8501-1, which is a hardcover 74-page book, and the actual official reference.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

August 26, 2009

Q. I want to know what the term "Sa" in blasting standards actually stands for.
My boss always asks me and I cannot answer. Help me please...

Ahmad Sanusi
Painting Executive - Johor, Malaysia

September 5, 2009

A. SA stands for Standard Abrasive ... Similarly ST means Standard Tooling

Rahul T.
- Mumbai, India
October 28, 2009

A. Sa Simply stands for Sand as that is the abrasive medium that they used to determine the blasting standards on the 4 Rust Grades for ISO 8501-1 [link by ed. to spec at TechStreet].

Remember Sand was the most widely used abrasive back in the days before the health risks of silicosis were identified.

Alternatively St stands for Steel sorry its nothing more technical, but that's it guys, and the reason I know is that I asked SIS years ago when I first started Inspection to settle an ongoing debate between myself and a colleague.

The relationship between the standards Sa3 and 2.5 is practically identical except that a 2.5 allows for staining or traces of contamination i.e. Very thorough blast cleaning. When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and from mill scale, rust, paint coatings and foreign matter. Any remaining traces of contamination shall show only as slight stains in the form of spots or stripes.

And Sa3 does not have any visual contamination present it is a white metal finish.

For a more definitive view at amounts of contamination which are allowed visually to be included in a blast please take a look at the joint Nace SSPC blasting standards which are equivalents, however not identical to the ISO 8501-1 standards. These standards give a better representation of the actual amounts of contamination which should be present.

Nace 1, SP5, Sa 3 = 0%
Nace 2, SP10, Sa2.5 = 5% Staining
Nace 3, SP6, Sa2 = 33% Staining
Nace 4, SP10, Sa1 = 100% as long as its tightly adherent

Lee Wilson Nace Level 3 Coating Inspector, Nace CIP Instructor & Lecturer, Icorr Level 3 Painting Inspector
inspection services - United Kingdom

February 5, 2010

thumbsup2Thanks a lot everyone. It was really helpful.

Priya Suryakant
- Bangalore,Karnataka, India

June 4, 2010

Q. Dear Sir,

I want to know about the detail of SA 2.5 about blasting for steel equipment.


Shanthi K
project engineer - Chennai,Tamil Nadu, India

June 4, 2010

A. Hi, Shanthi. The general meaning of Sa 2.5 is explained above.

My understanding is that the full details are covered by specification SS 55900, available from the Swedish Standards Institute at -- but that this standard was actually canceled in 2001 and is now superseded by ISO 8501-1 [link by ed. to spec at TechStreet].

Good luck.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

ISO 8501-1:1988

June 9, 2010

A. The blasting standards as depicted in ISO8501-1 are visual standards for surface cleanliness

Once a substrate is abrasive blasted the blast achieved is then compared to the visual reference pictures which are contained within ISO8501-1 and a comparison made between the blasting standard achieved and the standard required.

When you speak of Ra you are speaking of surface profile, roughness or anchor pattern which is the peak to trough amplitude of the blast profile usually expressed and specified in microns and created during the blasting process this is usually measured with surface replica tape, surface comparators or surface profile needle gauges however surface profile is not an indication of the surface cleanliness do not get confused surface profile and surface cleanliness as depicted in ISO8501-1 are separate requirements.

I hope that this helps

Best Regards

Lee Wilson Nace Level 3 Coating Inspector, Nace CIP Instructor & Lecturer, Icorr Level 3 Painting Inspector
inspection services - United Kingdom

January 17, 2011

Q. I would like reference/guidance for the relation between cleanliness standard with steel structural condition/type. Example: SA-2.5 is applicable for a structure on what conditions? Or what grade is suitable with what condition of structure?

Yuhanas Yuhanas
structure engineer - Jakarta, Indonesia

May 11, 2011

A. Sa.2.5 is expected for existing structure, while Sa.2 is for new installation.

Joseph Okoye
- Ikoyi, Lagos, Nigeria

May 5, 2011

Q. Sir
Can we use silica sand in following Sa 2.5 & Sa 3? If not, which kind of sand do we use?

Rana Akbar
employee - Rahim Yar Khan, Pakistan

August 21, 2011

Q. Which term to follow regarding surface preparation of storage tanks, whether surface cleanliness or surface profile or both because both seems two different requirement of surface preparation for applying coating on metal surface.

A. Aziz
- Karachi, Pakistan

October 1, 2011

A. It seems there is a whole book to be written on the blasting standard requirements, the differences between the required grades and surface profiles.
In short, our company approach the problem as follows:
The client needs to decide (or be advised depending on the application) what type of coating will be applied to the steel, this will decide the required blasting grade as specified by the coatings manufacturer (the norm seems to be SA2.5).The coatings manufacturer will also specify the required DFT (Dry Film Thickness) of the required coating to be applied.The DFT requirement is what needs to be looked at when one decides the roughness of a surface profile in microns.

Hans vd Linde
- Alberton, Gauteng, South Africa

October 26, 2011

Q. Please advise me how to inspect sand blasting for steel structures like I beam, channel, plate.
1. What the pressure should I maintain to get the fine surface preparation.
2. What microns should be there after sand blasting.

Mohamed Jaseem
quality control - Saudi Arabia

October 28, 2011

Q. I have a similar question to the one asked on October 26. For us we are being asked to prepare metal surfaces by Sandblasting to a Sp-10 level finish. What does that entail and how do we inspect for this?

Carlos Mdeleted
manufacturing - Stockton, California

Hi Carlos. Some people spend their entire careers helping people answer that question, so I can't pretend that it's easy. But if you have a copy of SP-10, please try your best to phrase your questions in terms of what information you feel is lacking in that specification. If you don't have a copy of SP-10 in your possession yet, well, you probably shouldn't proceed until you do :-)

Luck and Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

December 31, 2011appended

Q. Is it possible to achieve surface roughness 6.3 Ra from initial surface roughness 12.5 Ra by grit blasting with SA1 or SA1-1/2? Material forged steel.

Abdullah Ansari
wind energy - Pune, Maharashtra, India

January 19, 2012

A. Are you sure you are talking Ra? I don't think you can achieve those results using any blasting media.

AF Kenton
Nova Finishing Sytems Inc. - Hatboro, Pennsylvania

February 1, 2012

Q. For example: machined surface roughness Ra 12, can we blast it to SA 2.1/2 and achieve surface roughness 6.3 Ra?

Abdullah Ansari [returning]
wind energy - Pune, Maharashtra, India

February 2, 2012

A. Hi, Abdulah. I think AF (Tony) told you "no". To the best of my knowledge, blasting is for cleaning (removing surface contaminants), and I have personally never heard of anyone attempting to polish an article by blasting, so I think he's right.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

P.S. Jan. 2015: Upon re-examination, Abdullah is talking about 6.3 microns not 6.3 microinches; this is not "polishing" and probably is achievable by blasting in some fashion; but I do not have the necessary experience to answer the question of whether or not it is practical to simultaneously blast forged steel to Ra 6.3 microns and Sa 2.5.

January 25, 2012

Q. What is the size and specification of SA2.5 iron grit?

Ashok Kumar
- India

February 17, 2012

A. Dear Mr. Ashok Kumar, Sa 2.5 is a surface cleanliness level. So how can know grit size?
Sohail Hashmi

- karachi, Pakistan

April 13, 2012

Q. 1.What is the max.percentage of humidity to conduct sand blasting of steel structures?

2.How to measure the profiles SA2,SA2.5 & SA3 at site?

Please help me by answering these questions<

B V Ganeswara Rao
- Vishakhapatnam,AP,INDIA

May 8, 2012

Q. Dear Sir,
What is the specification grade for normal surface cleaning by hand before painting?

Subramanyan V A
- Calicut,Kerala, India

July 10, 2012

Q. How can we convert Sa 2.5 to millimeters?

- thrissur, kerala, india

July 10, 2012

Patron: "Waiter, my strawberries & cream have mud in them! Did you wash them?"

Waiter: "No problem sir, we can re-slice the berries smaller if the chunks are too large for your taste".

A. Hi cousin Sunilantonyt --

Please start at the top of this page and read it slowly and patiently to understand that Sa 2.5 is a visual standard for cleanliness, like the patron is talking about. It is not a measurement of surface profile like the waiter is talking about -- and no conversion between the two is possible. Good luck.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

August 21, 2012

Q. Could you tell the difference between rust grades A and B blasted to Sa3?

Almer G.
- philippines

October 16, 2012

Q. What is the meaning of "Degrease" according to SSPC SP1, and Profile 75, Profile 75µm

Javeed Akhlaque
- Pakistan

August 11, 2013

Q. I want clear Visual Photo or Reference of Sa 1 to Sa 3 value after Shot Blasting on HR Sheet (thickness 8-10 mm).

- Jamshedpur, Jharkhand

July 2013

A. Hi Arijit. Please carefully read the page. I already answered that question on October 21, 2012: "HMG Paints Ltd. offers a free 24-page PDF with pictures of these surfaces at:". Good luck.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

August 25, 2013

Q. Sir,
What surface profile is for Sa 2.5 sand blasting?

- AbuDhabi, UAE

August 2013

A. Hi Boby. Perhaps we continue to misunderstand each other's words and phrases, but many people have tried to make it clear that Sa 2.5 is a visual standard for cleanliness and it has nothing to do with surface profiles, which are measures of roughness not cleanliness.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

September 12, 2013

Q. As per customer, requirement is sa2.5 -- but we did sa3. Is there any problem?

thiruppathi manikandan
oil field services - hidd, manama,bahrain

September 2013

A. Hi Thiruppathi. I'm not an expert in this subject, but I can't imagine how it could be a problem. It sounds to me like you've simply removed any doubt that the surface is clean enough to comply with Sa2.5. Good luck.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

October 15, 2013



Manufacturer of LPG Cylinders - DELHI INDIA

October 16, 2013

A. Hi Shriram. This is available for Rs 130 either from Jain Book Agency at or direct from the Bureau of Indian Standards at

Good luck.


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Ted Mooney, P.E. RET
Pine Beach, New Jersey

February 24, 2014

Q. Dear sirs,

What is the full form of Sa In Swedish Blasting standard?
My answer was degree of cleanliness in an interview. But interviewer was not satisfied with my answer. The interviewer was From United States in SADARA project at Jubail in Saudi Arabia. So please send answer as soon as you can.

birendra Kumar Kathbaniya
- Dammam, Saudi Arabia

February 2014

A. Hi Birendra. Some have said Sa stands for "standard abrasive", others say it stands for "sand". I say it doesn't matter and you can't translate abbreviations from one language to another anyway :-)

But perhaps the interviewer's problem with your answer is that "degree of cleanliness" may not have quite conveyed the nature of ISO-8501-1 and the ratings like Sa 1, Sa 2, Sa 2.5 and Sa 3 that are associated with it. I think the main point, which is made several times in this thread, is that it is a standard which includes 24 photographs and is a guide for "Visual assessment of surface cleanliness". Please download the short free booklet from HMG Paints that was previously mentioned and I think you will understand it thoroughly. Good luck.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

May 13, 2014

A. SA:Sweden Airblast
ST:Sweden Tool

Derek Satre
- Medicine Hat, Alberta, Canada

July 29, 2014

Q. Dear sir,

I want to know about the Swedish standard SA-2.5, i.e., to check surface roughness in microns.

With regards


Rohan jena
- Odisha,india

July 2014

A. Hi cousin Rohan. Please study this thread and you will learn that your question isn't properly formed -- because SA-2.5 has nothing to do with microns or surface roughness. Good luck.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

sidebar2 October 8, 2014

thumbsup2Hi Ted,

I said 'Arrrgh' so many times when reading this page. You are a very patient man, and generous with your knowledge. If I could apologise for the blatant ignorance, I would.

Thank you


Matthais DeSOUZA
- Mumbai, Maharashtra, India

October 2014

Thanks Matt. I have the world's best job: I receive & post people's questions & answers from my own home on on my own schedule, interject my personal opinions at my leisure, am free to google around whenever I find anything interesting, and get paid for it all through advertising revenue. Yes, it means that I sometimes have to deal with a lot of repetition -- but that's a very small price to pay for not having to deal with the much harder stuff that most workers face :-)

I wish I could save the fast learners from the boredom of repeated answers, but since I haven't figured out how to do that, all I can do is try to make the site a fun and pleasant place to visit. Thanks again!


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Ted Mooney, P.E. RET
Pine Beach, New Jersey

January 10, 2015

Dear Sir,

I read the entire communication on this page since from the beginning ...

It is clearly mentioned that "Surface roughness" cannot be the outcome of blasting process and it isn't measurable also - NO standard calls...

But I observed one table for standards of surface preparation for steel in which ISO 8503-1:2012 calls for surface roughness characteristics of blast-cleaned surface..

Anyone can assist me in getting more details in the same

Adik Chavan
- Pune, India

January 2015

Hi cousin Adik. Thanks for your patience in reading the whole thing.

Unfortunately I do not have all of the standards that people mention on this site. But ISO 8503, which you are talking about, is not the ISO 8501 that others were talking about. ISO 8501 is the "visual standards for cleanliness", and this is what cannot be equated to surface roughness because it is a visual standard for cleanliness and not a roughness standard. We gave an analgous example that strawberries can be clean or dirty irrespective of the size of the slices.

ISO 8503 appears to be "surface roughness" standards, not visual cleanliness standards.

I don't believe that anyone said that surface roughness "cannot be the outcome of a blasting process and it isn't measurable". The whole point of ISO 8503 seems to be that it can be the outcome of blasting and it is measurable. Anthony Kenton and myself did express the opinion that it was probably not practical to achieve an Ra 6.3 polish by blasting, but I think I may have been hasty :-(
I, and probably Mr. Kenton, was thinking in microinches instead of microns, but upon re-examination microns were intended and Ra 6.3 microns is probably doable by blasting -- which is not to say that Abdullah Ansari will be able to achieve what he wants; I don't know.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

February 25, 2015

Q. I want to know if it is necessary to measure temperature & humidity of surface which is to be sand blasted.

Yogesh Bhujbal
- Satara, Maharashtra, India

February 2015

Hi Yogesh. I hope some reader fully understands the context of your question because it is too abstract for me. If you are a local weld shop offering to clean up a customer's old lawn mower, the answer is no. If a specification you are processing to requires it, the answer is of course yes.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

March 3, 2015

To add to Ted's answer. We also need to know what materials you are working with. You should also be aware that oxidation is always a problem which is caused by temperature and humidity.

AF Kenton
Nova Finishing Sytems Inc. - Hatboro, Pennsylvania

February 14, 2015

Q. I understand from reading the posts that we need to differentiate between surface cleanliness and surface profile.

An earlier post indicated that surface profile can be related to overall DFT.

Are there any guidelines as to what surface profile should be provided for differing DFT's?

Also, I see specifications from customers that stipulate different Ra ranges for carbon steel and stainless steel for the same paint system and DFT - why is this appropriate if the DFT is consistent?

- Manchester, United Kingdom

March 18, 2015

Hi Rob. One thing to keep in mind is that a thick coating on a very smooth surface does not stick as well, in many cases, compared to the same coating on a lightly roughened surface due to a smaller surface/contact area. Therefore, if adhesion is critical and the coating is fairly thick, 63 Ra or higher may be appropriate. On the other hand, if a given coating is very thin, perhaps a very fine finish such as 8 or less will work fine. Another example is a case where visual differences are desired. If a thin coating is placed upon a highly polished surface, the article will possibly look very different (shinier) than a case where the same coating is placed upon a mill finish or roughened article. However, if the DFT is quite high, the underlying Ra is less noticeable. After plating, the surface roughness should not change very much in most cases.

blake_kneedler Blake Kneedler
Santa Clara, California

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