Using Supplementary Safety Symbols

This month we look at what “supplementary symbols” are – and how and when to use them on the safety labels on your products.

When it comes to the main standards to help guide your product safety label content and symbol choices, domestically, it’s the ANSI Z535.4 Standard for Product Safety Signs and Labels, and internationally, it’s ISO 3864 – 2 Graphical symbols – Safety colours and safety signs – Part 2: Design principles for product safety labels. While these standards provide a framework, a building block, there are often gray areas around exactly how to apply them. In this article, we’ll explore common questions around the use of “supplementary symbols” on your labels.

Symbol Formats According to ISO 3864-2

To understand what’s meant by a “supplementary symbol,” having an overview of the latest update to ISO 3864-2 is helpful. A revised version of the standard was published in 2016, and included significant changes to label format options, including symbol use. Per this latest version of ISO 3864-2, the label format that used one, single non-ISO-formatted safety symbol was removed from the standard. Additional, “supplementary” safety symbols can be used – as long as the label has at least one ISO-formatted symbol. The “general warning sign” that serves as the safety alert symbol on the label’s severity level panel does not count as the ISO-formatted symbol; you need to use both a safety alert symbol and another ISO-formatted symbol on your safety label in order to follow ISO. (Note that an exception to this is symbol-only labels, a label format included in ISO 3864-2, which does not require a safety alert symbol.)

A Detailed Look at ISO Symbol Terminology and Shapes

Let’s dig deeper into some of the terms used above to fully understand the ISO-formatting options.

  • General warning sign: The general warning sign, a black exclamation point inside a black-banded yellow triangle, is a symbol used to alert users to potential hazards. See Figure 1.
  • ISO-formatted symbols: ISO-formatted safety symbols use a colored surround shape (a triangle, circle, or square) to define their overall safety function and to make them more easily noticed and recognized. This contrasts with ANSI Z535 where safety symbols may or may not use a surround shape. See Figure 2.
  • Supplementary symbols: ISO defines safety symbols as “supplementary” if they do not use ISO-colored surround shapes; typically they are reproduced in black and white. Supplementary symbols can use any line widths as they’re not bound by the design rules of ISO 3864-3. See Figure 3.

Figure 1: The general warning sign, according to ISO, standardized as ISO 7010-W001.


Figure 2: ISO surround shapes for a warning symbol, mandatory action symbol and prohibition symbol. ISO defines five types of safety symbols, each with its own combination of color, contrast color and shape; these three are the ones of particular interest for product manufacturers.



Figure 3: An example of a safety label that meets ISO 3864-2 requirements with an ISO-formatted safety symbol (the symbol related to arc flash, at left), and includes a supplementary safety symbol (the symbol related to disconnecting electrical power, at right). (Label design ©Clarion Safety Systems).

Putting Supplementary Symbols Into Practice

Safety label design and symbol use are not always entirely straightforward when it comes to putting best practices into action – all while aligning with your product and its environment of use and lifecycle, as well as your market and audience. Case in point: the ISO 3864-2 standard includes several informative annexes with pages and pages of guidelines, examples, and safety label development considerations.

According to Angela Lambert, Director of Standards Compliance at Clarion Safety Systems, while working with the company’s product manufacturing clients as well as with standards-related stakeholders, she sees several common questions related to the use of supplementary symbols. Here are those main themes, along with helpful tips from Lambert to keep top of mind:

  • Audience: Consider whether your audience is primarily U.S.-based or international, and whether your focus is on adhering to ANSI or ISO product safety label standards. Whether you choose to follow the ANSI or ISO standards will effect the type – and potentially quantity of – symbols that you use. “If you’re only concerned with following ANSI standards, you may choose to use a non-ISO formatted safety symbol, while to follow the ISO standards, you’d also need to include an ISO-formatted symbol,” says Lambert.
  • Space/legibility: “One potential downfall of using an ISO-formatted symbol can be losing some legibility or detail of the symbol, especially when space is an issue,” Lambert says. Symbols can be reproduced larger when not in a surround shape. “If your goal is to comply with the ANSI standards, and space or legibility is an issue, that may impact your decision to include the surround shape of an ISO-formatted symbol or to include a supplementary symbol.”
  • Multiple symbols: The use of multiple symbols on safety labels can be helpful to reinforce each other and to convey more complete information, such as both hazard description and avoidance. “I advise using multiple symbols, or supplementary ones, mainly based on the audience and the requirements at hand. For example, if I’m working with a manufacturer shipping products into Japan who is not planning to translate their labels from English to Japanese, it would be important to use an ISO-formatted symbol, and potentially include a supplementary symbol in order to reinforce the English word message to non-English speakers.”
  • Consistency: “While there’s not one steadfast rule when it comes to how you should label your products –
    or the symbols you use on them – your overall goal should be creating systems of labels that are consistent across product lines and markets. Keep that in mind when choosing your label design and symbols, in line with your product’s risk assessment and market requirements,” Lambert says.

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This article is courtesy of Clarion Safety Systems ©2019. All rights reserved.

Erin Earley
, head of communications at Clarion Safety Systems, shares her company’s passion for safer products and workplaces. She’s written extensively about best practices for product safety labels and facility safety signs. Clarion is a member of the ANSI Z535 Committee for Safety Signs and Colors, the U.S. ANSI TAG to ISO/TC 145, and the U.S. ANSI TAG to ISO 45001. Erin can be reached at

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