Prohibition Signs: Colours, Symbols and Meaning Explained

What is a prohibition sign?

A prohibition sign communicates a specific action that is not allowed. The design is intentionally simple so the message is understood quickly: a red circular ring with a diagonal red bar overlays a black symbol on a white field. The message can be reinforced with concise text below the symbol (for example, “No smoking”).

These signs are common on construction sites, in warehouses, healthcare facilities, hospitality venues, schools and public spaces. They help prevent unsafe behaviour, protect equipment and meet organisational safety policies.

Shop prohibition signs or request custom wording/sizes. Need a fast quote? Send your specs to our team and we’ll produce to Australian standards and your site requirements.

Sign Portal holds a large in-house library of compliant pictograms and standard messages, enabling fast turnarounds on common sizes (for example 150 mm, 200 mm, 300 mm circles and 300 x 450 mm panels with text). Our production team can match your site program for consistent layouts and document control.

Colour and shape codes

Prohibition signs rely on universal visual cues to deliver a fast “do not” message. While different workplaces may have their own sign programs, the visual language is consistent and widely recognised.

• Primary colour: Red circular border and diagonal red slash.
• Background: White field to maximise contrast and legibility.
• Symbol (pictogram): Black, centred within the circle.
• Shape: Circular device with supplementary text panel as needed.

The red slash always cuts across the prohibited action. If text is used, keep it short, active and unambiguous (for example, “No entry”).

• Best-practice proportions: Annulus (red ring) thickness typically around 10% of the circle diameter; the diagonal bar the same thickness, set at approximately 45°.
• Hierarchy: Symbol first for instant recognition; keep any text secondary and concise.
• Contrast control: Avoid placing red elements on red backgrounds; maintain clear white field around the device.

Common symbols and their meaning

Symbols make prohibition signs fast to understand, even for non-native English speakers. Below are typical pictograms and what they mean in practice.

• No smoking: Cigarette with smoke crossed out. Prohibits smoking in the area.
• No entry (authorised persons only): Person silhouette or doorway crossed out. Limits access to trained or cleared personnel.
• No mobile phones: Handset crossed out. Prevents distraction, interference or ignition risk.
• Do not operate: Hand or lever crossed out. Leaves equipment isolated or locked out for safety.
• No pedestrians: Walking person crossed out. Keeps foot traffic out of vehicle or plant zones.
• Do not use lift in fire: Lift symbol with flames crossed out. Directs people to stairs during fire emergencies.
• No cameras: Camera crossed out. Protects privacy, IP or sensitive operations.
• No food or drink: Cup/utensils crossed out. Controls contamination in labs or production areas.
• No vaping: E‑cigarette crossed out. Aligns with smoke-free policies in and around buildings.
• No ignition sources: Match/flame crossed out. Used at fuel decanting and hazardous area boundaries.

We can combine multiple prohibitions on a single panel for tidy entry points and control rooms. Ask us about custom combination boards with your site logo and document control fields.

When to use and where to place

Use a prohibition sign when a specific unsafe action must not occur in a defined location. Choose symbol-only for quick comprehension or add text to remove any doubt about what is banned and where the rule applies.

• Line-of-sight: Place at decision points (entries, doorways, switches, controls) where behaviour is chosen.
• Height and distance: Mount so the symbol is easily seen from the normal approach distance.
• Lighting and contrast: Ensure visibility in the site lighting conditions; avoid visual clutter.
• Redundancy: Repeat on long approaches or large areas so the rule remains clear.

Materials and durability options

The right material depends on exposure, impact risk and whether the sign is temporary or permanent. At Sign Portal we manufacture prohibition signs in-house using industrial printing and cutting equipment, matching materials to the environment.

• Self-adhesive vinyl decals: For doors, machines and smooth walls. Can be laminated for abrasion resistance and easy cleaning. Suitable indoors and, with the right film and laminate, outdoor use.
• Rigid plastic (polypropylene or similar): Lightweight, economical and non-corroding for indoor areas or sheltered outdoor locations.
• Aluminium composite panel (ACP/ACM): Rigid, dimensionally stable and ideal for outdoor and coastal exposure. Direct UV printed on our flatbed printers for crisp symbols and strong colour.
• Aluminium: Durable metal option for harsh industrial settings; compatible with mechanical fixings and VHB tape.
• Corflute: Temporary worksites, events and short-term controls where quick setup and low weight matter.
• Engraved phenolic/Traffolyte: High-contrast, solvent-resistant tags and machine plates where permanence and chemical resistance are priorities.
• Reflective film (optional): For low-light areas, we can produce prohibition symbols on RA1/RA2 reflective films for added visibility in torchlight and vehicle headlights (note: reflectivity is not required by AS 1319 but can aid recognition).

Australian conditions can be demanding: high UV, heat, tropical rain and coastal salt. For outdoor signs, consider UV-stable inks, durable substrates and protective laminates. Where chemicals or frequent cleaning are expected, choose films and laminates with appropriate resistance.

• Thickness options: ACP 3 mm for general outdoor; aluminium 1.6–2.0 mm where lighter weight is needed; polypropylene 1.4–3.0 mm for indoor plant rooms.
• Protective laminates: Gloss or matte; anti-graffiti film for public areas; textured matte where glare is a concern.
• Adhesives: High-tack for low-energy plastics; removable adhesives for temporary controls.

Typical build specs we supply for coastal sites: 3 mm ACP with direct UV print, anti-graffiti overlaminate, rounded corners (3–6 mm radius), and 316 stainless fixings. For smooth internal surfaces (doors, enclosures), a polymeric vinyl decal with a chemical-resistant laminate performs well under regular cleaning.

• Corner and hole options: 3–6 mm radius corners; 6–10 mm holes; slotted holes for fence mounting; hole centres to your template. We can match existing hole patterns for panel swaps.
• Structural bonding tapes: For clean, fast installs to metal or painted surfaces, VHB-style acrylic foam tapes paired with an adhesion promoter increase peel/shear strength. Combine with mechanical fixings where impact is likely.

Order ACP prohibition signs or order decals.

Sizes, legibility and layout

Bigger symbols are easier to recognise at a distance. Choose a sign size that suits the viewing distance, speed of approach and available mounting space. For corridors and doorways, a compact size can work; for vehicle zones or large open areas, step up to larger panels so the symbol and any text are unmistakable.

• Prioritise the symbol size; keep supplementary text short.
• Use high contrast: red on white with a clear black pictogram.
• Avoid stacking too many messages in one place—break them into logical groups.
• Where approach speeds are higher (vehicle yards), upsize panels so the symbol is legible in time to act.
• Common workplace sizes: 150–200 mm circles for doors and equipment; 300 mm circles or 300 x 450 mm panels for gates and approach points; 600 mm and larger where long viewing distances apply.

Symbols, text and custom wording

Symbols provide instant recognition; text removes ambiguity. Many workplaces combine both for clarity. Keep wording direct: “No entry”, “Do not operate”, “No mobile phones”. Avoid long sentences or softening language—prohibition signs communicate rules, not suggestions.

Comparison with other regulatory signs

It’s easy to confuse prohibition signs with other regulatory signs. The table below clarifies the key differences so you can select the right category for your message.

Compliance and Australian standards

In Australia, prohibition signs used in workplaces should follow the design principles in AS 1319—1994 Safety signs for the occupational environment. While ISO 7010 symbols are widely recognised internationally, AS 1319 remains the common reference for Australian workplaces. Always apply signs within a broader risk control program, not as a substitute for engineering or administrative controls.

• Use the red annulus/diagonal device with a black pictogram on a white field.
• Keep wording brief, direct and consistent with the symbol.
• Locate signs at the point of hazard or decision. Ensure adequate illumination and contrast.
• Do not mix categories (e.g., prohibition vs. mandatory) on a single device—use separate signs if needed.
• For road traffic applications, use the relevant road signage standards; AS 1319 is for occupational environments.

Helpful references:

• Safe Work Australia – Safety signs
• Standards Australia Store – AS 1319 (search)
• WorkSafe Queensland – Safety signs guidance

Manufacturing at Sign Portal

We produce prohibition signs in-house in our approximately 480 m² facility with clean, specialised print rooms. Direct-to-substrate UV printing on rigid panels delivers sharp pictograms and durable colour, while print-and-cut workflows create precise decals and labels.

• UV flatbed printing: Two Mimaki JFX EX flatbeds print directly to ACP and other rigid panels for outdoor-ready signage.
• Wide-format print/cut: Our Roland VG-640 produces high-quality decals and labels, with optional laminates for abrasion and chemical resistance.
• Laser cutting and engraving: The Trotec Speedy 500 and a large-format 230 W CO2 laser handle plastic panel cutting and durable Traffolyte tags.
• CNC routing: The MultiCam SM2412 provides clean edges and accurate holes/slots for posts, fences and machinery.
• RIP and colour control: ICC-profiled workflows in our RIP software with device calibration using an X‑Rite instrument ensure neutral blacks, consistent reds and repeatability across reprints.
• Adhesion and durability checks: We conduct on-substrate test swatches and cross-hatch adhesion checks on ACP and polypropylene before production runs to confirm ink/film bond strength.

Being Veteran-Owned with Local Buy credentials, we support government and enterprise procurement requirements, and we ship Australia-wide, including regional and remote delivery.

• Process control: On-substrate test swatches for adhesion and colour before production runs; surface prep with isopropyl alcohol; adhesion promoters on low-energy plastics as required.
• Colour management: ICC-profiled workflows for consistent reds and neutral blacks in prohibition symbols across materials.
• Edge finishing: Deburred, chamfered corners on rigid panels to reduce chipping and improve handling safety.
• Traceability: Optional job codes or QR stickers applied to the reverse for asset registers and re-ordering.

Order engraved Traffolyte prohibition tags for valves, switchboards and plant.

Installation methods

Choose fixings that suit the substrate and surface. Prepare surfaces by cleaning and drying before installation. Trial-fit in the intended line-of-sight before committing to fixings.

• Adhesive decals: Apply to clean, smooth, non-porous surfaces; use firm squeegee pressure. Consider edge sealing or lamination where frequent cleaning occurs.
• Rigid panels to walls/fences: Screws with washers, rivets, or VHB-style tapes on compatible, properly prepared surfaces. Use mechanical fixings where impact or peeling forces are likely.
• Temporary setups: Cable ties through pre-drilled holes for mesh fencing; removable tapes for short-term indoors.

In hot, cold or coastal environments, adhesives can behave differently. Where in doubt, combine mechanical fixings with adhesive for redundancy.

• Tamper resistance: Consider one-way screws or rivets in public spaces.
• Corrosion control: Use stainless fixings near coastal exposure; isolate dissimilar metals to avoid galvanic corrosion.
• Surface preparation: Degrease with isopropyl alcohol, then apply adhesion promoter on low-energy plastics before using acrylic foam tape. Avoid silicone-contaminated paints.

Browse sign hardware and fixings.

Maintenance and replacement

Regular checks keep messages clear and enforceable. Faded or damaged signs undermine safety and can create uncertainty.

• Cleaning: Use mild detergent and water with a soft cloth. Avoid harsh solvents that may damage inks, laminates or plastics.
• Inspection: Look for fading, abrasion, graffiti, peeling edges and loose fixings—replace as needed.
• Environment: High UV, tropical rain and coastal salt accelerate wear. Choose outdoor-capable materials and consider protective laminates.

Repair and refurbishment

Where practical, repair extends service life and reduces waste. Prioritise clarity—if a sign cannot be restored to full legibility, replace it.

• Decals: If edges lift, clean the surface, trim loose sections and apply a new over-laminate or replace the decal. For contamination under the film, full replacement is recommended.
• Rigid panels: Tighten or replace loose fixings. For minor scratches, fit a clear anti-graffiti laminate over the face after cleaning and decontamination. If the pictogram or red annulus is damaged or faded, replace the panel.
• Graffiti removal: Start with mild detergent; if needed use a plastic-safe citrus cleaner. Rinse thoroughly. Avoid ketones or strong solvents on printed faces unless protected by an anti-graffiti laminate.
• Bent panels: ACP/aluminium that has kinked should be replaced. Attempting to re-flatten can crack inks and weaken structure.
• Document control: Update asset registers and photo records after any repair. If the underlying risk has changed, reassess the sign type and location.

Field repair tips from our production team:

• Seal vulnerable decal edges with a compatible edge sealer after cleaning and drying to reduce water ingress in washdown areas.
• Fit nylon or rubber washers under screw heads on rigid panels to reduce point loading and vibration wear.
• Where a printed face has localised damage, we can supply a colour-matched repair decal sized to the symbol area to extend service life until the next change-out.

We offer rapid reprints and replacements using archived artwork. Ask about matching hole centres and sizes to swap panels without drilling.

Ordering checklist

Clear specifications speed up production and ensure you receive exactly what you need. When requesting a quote or placing an order, confirm:

• Message and symbol (for example, no smoking, no entry, do not operate).
• Material (decal, rigid plastic, ACP, aluminium, Traffolyte) and whether lamination is required.
• Size and quantity, plus hole positions or mounting method.
• Indoor or outdoor use; any exposure to chemicals, cleaning or coastal conditions.
• Any custom artwork requirements and file preferences (vector artwork recommended).
• Delivery deadline, site access requirements and any inductions needed.
• Corner radius, hole diameter and centres; reflective requirement (if any); anti-graffiti requirement for public areas.

Sustainability and end-of-life

Where possible, specify recyclable substrates and plan for responsible disposal at end-of-life.

• Aluminium/ACP: Separate metal from cores where facilities exist; reuse existing fixings where safe.
• Plastics: Check local recycling streams; avoid contamination with adhesives/solvents.
• Refurbish first: Add anti-graffiti laminate or replace decals on intact panels to extend life before full replacement.

Technical sources

• Safe Work Australia – Safety signs
• Standards Australia Store – AS 1319 (search)
• WorkSafe Queensland – Safety signs guidance
• Sign Portal – Prohibition Sign Manufacturing Specification (internal; available on request) covering symbol library, annulus/bar proportions, colour targets and QC checkpoints.
• Sign Portal – Adhesion and Durability Test Method (internal; available on request) outlining cross-hatch adhesion checks on ACP/polypropylene and cleaning resistance checks prior to release.
• Avery Dennison Anti‑Graffiti Overlaminate – Technical bulletin (reference for cleaning and graffiti removal compatibility).

Related products

• Prohibition signs – standard symbols
• No Smoking signs
• No Entry / Authorised Personnel Only
• Custom prohibition signs and multi-message boards
• Engraved Traffolyte tags – prohibition/lockout
• Adhesive decals – prohibition symbols
• Aluminium Composite (ACP) panels
• Sign posts, brackets and tamper-resistant fixings

Related Sign Portal resources: Prohibition - Do Not Wear Gloves Sign · Prohibition - Fire Naked Flame Prohibited Sign · Prohibition - This Is A Smoke Free Workplace Kindly Assist Sign