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Paint Markers for metal… what does “low corrosion” and “low chloride” mean?

Date: 17-03-2017

All about “low corrosion”, why it matters... and why the Markal Pro-Line HP from Weldclass is your safe paint marker for all metals!






Why is “Low Corrosion” important ?

  • As technology continues to advance, many industries such as food production & handling, power generation, oil refining, gas plants, mining, aerospace, shipbuilding, etc are relying upon stainless steel and various alloy metals for use in critical and sensitive equipment.

  • Unwanted corrosion can weaken or contaminate this critical equipment and cause dangerous health and safety risks.

  • Chemicals such as chlorides, other halogens, sulphur and low melting point metals which are often found in marking and paint products can contribute to unwanted corrosion, degradation, pitting, or general weakening of sensitive materials. To avoid this, it is important to use markers that are ‘low corrosion’.



What is the definition of a “low corrosion” Paint Marker ?

Whilst there is no national or international standards that define low-corrosion in respect to paint markers, the common accepted threshold for “Low corrosion” markers is those that have less than 250ppm (parts per million) of corrosion-causing substances… Or to be specific;

  • Less than 200ppm of Chlorides and total Halogens

  • Less than 250ppm of each low melting point metals (includes: Antimony, Bismuth, Cadmium, Lead, Mercury, Phosphorus, Tin, Zinc, Copper, Silver)

  • Less than 250ppm of sulphur



“Low Corrosion” and “Low Chloride” – what’s the difference ?

To be truly “low corrosion”, markers should not only be low in chloride, but must also have low content of other corrosive substances (sulphur, fluorides, halogens, low-melting point metals, etc).

Some markers may claim “low chloride”, but have unacceptably high content of these other corrosion-causing substances – therefore they are not truly “low corrosion”.



So how do I know that Pro-Line HP markers are low corrosion ?

All Pro-Line HP markers are formulated to be as low-corrosion as possible.

Specific common Pro-Line HP colours are Laboratory Tested (using typical analysis) to contain less than n 250ppm (parts per million) of chlorides and other corrosion-causing substances. These colours are: White, Yellow, Red, Black & Pink*

This is why these Pro-Line HP markers are specified and preferred by many workshops and sites across Australia. Using Pro-Line HP gives you peace of mind that the marker you use today won’t contribute to corrosion related problems on your metal structure tomorrow.

Click Here to view & download a fact sheet and test reports on Pro-Line HP. 



Is Pro-Line HP restricted to critical applications only? …Or can I use it as a general paint marker ?

The Pro-Line HP is used across Australia and the world as a general purpose industrial paint marker for almost any application you can think of… including; all metals, wood, plastic, masonry, glass, ceramic, rubber & more.  And Pro-Line HP works great on challenging surfaces such as damp, oily or rusty metal.

Pro-Line HP is truly one of the safest and most versatile industrial paint markers in the world!


Contact Weldclass today to request samples and find your nearest distributor, or Click Here for more information.





This blog is intended to help with: Preventing metal corrosion, rust, oxidisation, oxidation, pitting, etc caused by paint marker pens | What is the best paint marker to use on stainless steel?  |  What is the best paint marker for metal?

All specifications are subject to change without notice. While all care has been taken, Weldclass accepts no responsibility for any inaccuracies, errors or omissions in this information or links and attachments. Any comments regarding intended application are for description and identification purposes only. It is the sole responsibility of the user and/or owner and/or purchaser to select the appropriate product for their intended purpose and to ensure that the product selected is capable of performing correctly and safely in the intended application. E.&O.E. *Pink markers offered by Weldclass are the Markal ‘Valve-Action’ series which are grouped together with the Pro-Line HP series for convenience and identification purposes.


  • Date: 17-03-2020
    Charles Mathis

    Thank You For Your Information.
  • Date: 22-03-2019
    Weldclass Team JWL Marketing Pty Ltd

    Azevedo Joana – For all the reasons mention on this blog, Pro-Line HP is especially suited for use on stainless-steel. Marks are long-lasting, however as with any paint marker they will not last indefinitely. If you need a mark that will not come off under any conditions, you should consider etching / engraving.
  • Date: 22-03-2019
    Weldclass Team JWL Marketing Pty Ltd

    Atul - Pro-Line HP is recommended for marking on both painted & un-painted surfaces.
  • Date: 22-03-2019
    Azevedo Joana

    What's the best black marker for stainless steel marking? And I need it to not come off. Thank you
  • Date: 31-12-2018
    Atul kumar karn Tata steel limited

    We want to write on painted surface as well as on the steel plates for identification(tracibility purpose).please suggest the relevant markers with all its details.
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