When colors distinguish functional areas on a graphic overlay, also retain text, identifiers or symbols that convey the meaning independently. Review these non-color cues first, then check lettering, position and use conditions on the physical sample. Matching an approved color sample establishes color consistency; it does not, by itself, establish that functional markings are readable. This article addresses fixed printed markings on ordinary equipment. It does not prescribe colors for emergency stops, alarms or other safety markings.
A Central South University control-system procurement notice published on November 4, 2026 (Chinese) on the China Government Procurement Network lists local control boxes, PLC control systems and industrial touchscreens. The notice establishes procurement requirements, not completed delivery. It does not disclose graphic-overlay construction, color schemes or a Baoshengda supply relationship.
If your own project combines control boxes, touchscreens and separately purchased graphic overlays, the physical markings and screen prompts need consistent object names. For example, instructions for two ordinary display channels should not identify one only as “the red channel.” The following review uses this multi-interface context to examine non-color identification cues; it does not analyze the reported project's actual operating design.
Establish the meaning before assigning a supporting color
Review the artwork without relying on color: can the visible markings tell the reader what an area is called, what an identifier refers to, and what a symbol means? A grayscale version of a screenshot can help flag distinctions that rely only on hue. It is an initial screen, not a simulation of everyone's vision or a substitute for reviewing the assembled physical part.
W3C's explanation of WCAG 1.4.1, Use of Color, says web information should not rely on color alone; text or shapes can provide additional cues. This article borrows that information-design principle. WCAG addresses web content, not graphic-overlay product acceptance. Citing it cannot establish equipment accessibility or safety certification.
For example, suppose an ordinary instrument has display channels A and B, initially separated only by two background colors. The equipment owner could first approve the fixed names “Channel A” and “Channel B” and retain text or identifiers in the corresponding areas. If symbols are also used, define their meaning and direction rather than assuming every user understands an arrow. This is an artwork-review example, not a customer case or a validated design.
Check four types of artwork information separately
The table is a suggested project review for ordinary fixed markings, not a set of universal limits. Where several cues convey the same meaning, each should point to the correct object. Conflicting text, identifiers or symbols cannot be accepted merely because the colors look correct.
| Information | Question to resolve | Sample-review record |
|---|---|---|
| Function text | Without naming a color, can the reader identify what the area means? | Approved wording, actual lettering, viewing position, and misread or unreadable items |
| Identifiers and positions | Does each identifier refer to the same device, channel or window rather than a temporary spoken alias? | Mapping to the equipment owner's object list; any housing obstruction after assembly |
| Symbols and directions | Is the meaning approved, and does the direction match the actual object? | Original symbol artwork, approved meaning and assembly orientation; file names do not define meaning |
| Color | Is it a supporting cue, decoration, or the only carrier of particular information? | Approved sample and agreed evaluation conditions; separate conclusions for color consistency and recognizable meaning |
Fixed printing cannot report a changing state
A state name printed on a fixed panel labels the purpose of that position; it does not establish the equipment's current state. If a screen or indicator reports the state, separately confirm its relationship to the fixed markings. Where software switches between channels A and B, identify where the current selection is visible. A fixed background color is not the live selection result.
Returning to the control-box and touchscreen context, the equipment owner can provide one object list and compare overlay wording, screen names and documentation against it. Leave unapproved color meanings unresolved. The printing supplier should not independently interpret a color as start, stop or fault. Markings subject to regulations, equipment standards or risk assessment require the equipment owner to determine the applicable requirements separately.
Approve readability and print consistency as separate results
Record sample, artwork and assembly revisions. Agree lighting, viewing position, distance, angle and the states in which the equipment will be used. The project defines acceptance criteria; this article provides no universal font-size, color-difference or contrast values. Separately record comparison with the approved color sample and correct object identification. Photos, screen previews and grayscale screening alone cannot replace these physical results.
Shenzhen Baoshengda Technology Co., Ltd.'s graphic-overlay and keypad-overlay customization page (Chinese) describes project discussions based on artwork or samples, covering lettering, colors, textures, windows, cutouts and adhesive, with assembly checked against the housing and display module. Provide approved object names, original symbols and a position drawing, then ask Baoshengda Technology to confirm the specific surface-part manufacturing and sample scope. The public information does not establish equipment-level human-factors, accessibility or safety validation.
A graphic overlay or keypad overlay supplied alone does not include switch circuitry. If metal domes are combined with the customer's PCB, identify PCB and functional-validation responsibilities separately. The cover shows square and triangular graphics, a window and a tail on an existing sample. Image annotations are not this project's symbol definitions, material identification or test evidence.
For a disagreement about color consistency between batches, see graphic-overlay color acceptance (Chinese). To hand approved text and symbols to the manufacturer, use the artwork handoff checks (Chinese). When sharing artwork through the project contact page, distinguish approved meanings from items awaiting the equipment owner's decision. A color name cannot replace the complete definition. The English graphic-overlay product page provides the related product scope.