How to Call Out Mold Texture on an Engineering Drawing

A mold texture drawing callout must state eight things: the finish system and grade or pattern, the surfaces that carry it, the surfaces that do not, the depth the draft was designed for, the direction of any directional pattern, the physical approval reference, how gloss is recorded and when the texture is applied. A one-line note such as "TEXTURE: VDI 30" answers only the first item and leaves the other seven to whoever reads the drawing.

By the Mold Texturing Guide editorial team. Last reviewed: October 20, 2026

Why one-line texture callouts fail

The part drawing is the only document read by everyone in a textured program: the product engineer who writes it, the toolmaker who builds the steel, the texturing shop that etches or lasers the cavity, the molder who runs the tool and the quality engineer who accepts parts. Each of them reads the texture note with a different question in mind. The toolmaker wants to know which surfaces to leave for texture and how much draft is enough. The texturing shop wants to know where the pattern stops. The quality engineer wants to know what "correct" looks like and how to measure it.

A note that names only the grade answers none of those questions. Each reader fills the gaps with a local habit, and the habits rarely match. The result shows up late: a pattern that runs over a sealing land, a drag mark on a wall that had polished-surface draft, a gloss dispute between two plants molding the same part, or a re-texture that cannot be matched because nobody recorded what was approved.

None of these problems is caused by the texture itself. They come from what the drawing did not say. The fix costs a few lines of notes and one physical reference that everyone signs.

What the standards define and what they leave to you

Several documents touch a texture callout, and none of them covers the whole job. Knowing where each one stops tells you what the drawing notes have to add.

The practical conclusion is simple. A roughness symbol controls a measurable parameter. A decorative texture is a visual requirement, and visual requirements are controlled by a physical reference plus a written note. Most textured cosmetic surfaces need both: the note to define scope and the reference to define appearance.

The standards above are cited by number for identification only. For contract use, work from the current editions issued by ASME, ISO, ASTM and VDI.

The eight elements of a complete texture callout

1. System and grade or pattern

Name the system every time. "Texture 24" is ambiguous; "VDI 3400 GRADE 24" is not. For VDI grades, add the reference Ra in both units so the number survives a metric shop and an inch shop. VDI 3400 grade 24 corresponds to Ra of about 1.58 micrometers, or 62 microinches. For SPI grades, write the grade and the system, such as "SPI C1". For a supplier pattern, write the supplier name and its pattern code exactly as the supplier publishes it, and treat the code as an identification of the pattern, not as the requirement. The requirement is the approved reference in element 6. You can compare the three systems on the SPI, VDI and Mold-Tech conversion page.

2. Textured zones

Label every textured surface on the views with a zone code and define the code in the note. Zone labels survive model changes better than descriptions such as "all outside surfaces", which nobody interprets the same way once ribs, bosses and shut-offs are involved. Two or three zones are typical on a housing: the main cosmetic face, a secondary face with a finer or different finish, and everything else.

3. Exclusions

Texture where it does not belong causes functional failures. List the features that stay untextured: sealing lands, shut-off faces, parting line lands, snap rails, datum features, label areas and any surface with a functional roughness requirement. If an excluded feature sits inside a textured zone, show the boundary on the view.

4. Design depth

Draft on a textured wall depends on texture depth, not on the grade name. A widely published starting rule adds about 1 degree of draft per 0.001 in (0.025 mm) of texture depth, on top of the draft the part needs without texture. Because pattern depth varies by supplier and process, the drawing should state that the texturing supplier confirms depth and minimum draft for each zone before the steel is cut to final. The draft angle by texture page explains the rule and its limits.

5. Direction

Leather grains are mostly non-directional, but brushed lines, wood grains and many geometric patterns have a direction. Show it with an arrow on each zone and reference the arrow in the note. Direction also matters for ejection: a pattern whose lines run across the pull direction is harder to release than one running with it.

6. Approval reference

The approval reference is a physical object: a plaque or molded sample in production resin and color, signed and identified with an ID. On this site that object is called the acceptance master. The drawing should cite its ID, state that it governs appearance and say where the controlled copy is kept. Photos are useful for tracking, but they hide depth, gloss and color shifts, so they should never be the approval.

7. Gloss

Two parts can carry the same texture and still look different because their gloss differs. Record gloss at approval with a glossmeter per ASTM D523, and state the geometry. The standard uses 60 degrees for most surfaces, 20 degrees for high gloss and 85 degrees for low gloss, which is where most textured parts fall. A gloss value recorded at approval also gives you an objective way to detect wear later in production. See gloss levels and gloss units for how to read the numbers.

8. Release condition

Texture should be applied after the tool has passed tryout and dimensional approval. Changing steel after etching means welding or machining a textured surface, which rarely matches. A one-line release note prevents that and gives the toolmaker a clear point in the schedule.

Worked example: from one line to a complete note block

The original note on a housing drawing read:

The complete version below answers all eight elements:

Illustrative example. Not a customer case. The zones, draft value and acceptance master ID are invented for this example; adapt every value to your part and confirm depth and draft with your texturing supplier.

Notice what changed. The grade is still there, but now it has a system, a reference value in two units and a zone. The exclusions protect function. The draft line ties the design to the real texture. The acceptance master settles appearance. The gloss line makes appearance measurable. The release line protects the schedule. Note 7 closes the gap that offshore transfers and second sourcing usually open.

Roughness symbol or texture note: which one to use

Engineers trained on machined parts often reach for the surface texture symbol first. The symbol is the right tool when the surface has a functional roughness requirement that someone will measure: a sliding face, a sealing surface, an optical zone with a roughness limit. On those surfaces, use the symbol per ASME Y14.36 or ISO 21920-1 and the measurement basis per ASME B46.1 or the ISO equivalent.

A decorative texture is different. A leather grain or a stipple can have the same Ra as another pattern and look nothing like it. Ra describes average height deviation; it says little about pattern shape, spacing or how light scatters. For cosmetic texture, use the note and the acceptance master, and give the Ra only as a reference value when a grade system such as VDI 3400 is used. The page on surface roughness parameters explains why Ra alone cannot describe a decorative surface.

Failure modes a complete callout prevents

• Texture on a sealing land. The note said "all external surfaces". The gasket face was external. Prevention: an exclusion list and a boundary on the view.
• Drag marks on textured walls. The toolmaker used polished-surface draft because the drawing did not tie draft to depth. Prevention: element 4, with supplier confirmation before final steel.
• Two plants, two looks. Each plant approved against its own sample. Prevention: one acceptance master with an ID, and controlled copies made from it.
• Gloss dispute after six months. Parts looked shinier, but nobody had a number from approval. Prevention: gloss recorded at approval with the geometry stated.
• Re-texture that does not match. A late design change required welding a textured cavity. Prevention: the release condition, so texture is applied after dimensions are frozen. See mold texture repair for what happens when it is too late.
• Silent substitution. An offshore toolmaker's texture partner used a similar pattern from another library. Prevention: note 7, which requires written approval and a new signed acceptance master.
• Unit mix-up. A reference value of 62 was read as micrometers instead of microinches, a factor of about 39. Prevention: both units on every reference value.

Checklist before releasing the drawing

• Every textured surface carries a zone label, and every zone is defined in the note.
• The system is named with each grade or pattern, and reference values appear in microinches and micrometers.
• Sealing lands, shut-offs, parting line lands, snap rails, datums and label areas are excluded by name.
• Draft on textured walls is tied to texture depth, with written confirmation from the texturing supplier.
• Directional patterns show an arrow on each zone.
• The acceptance master has an ID, is molded in production resin and color, and its controlled copy has an owner.
• Gloss is recorded at approval per ASTM D523 with the geometry stated.
• Texture is released only after dimensional approval.
• Substitution of process or pattern requires written approval and a new signed acceptance master.

Should the drawing name the texturing supplier?

Usually not. Naming a pattern library identifies a pattern, which is fine. Naming a specific shop locks the purchase, which belongs in the purchase order or the RFQ, not on the part drawing. If the program requires a specific source, for example because the customer approved a pattern from one supplier only, put that requirement in a controlled specification referenced by the drawing.

Can "or equivalent" be used in a texture callout?

It can, but only with a defined approval path. "VDI 3400 grade 30 or equivalent" invites every supplier to decide what equivalent means. If you allow alternates, state that any alternate requires written approval and a new signed acceptance master. That keeps flexibility for sourcing without losing control of appearance.

Where should the acceptance master be kept?

The governing acceptance master stays with the party that signs parts off, usually buyer quality. Controlled copies, molded from the same approved tool condition and identified as copies, go to the molder and, when needed, to the texturing shop. Each copy should carry the master ID and its own copy number. When the tool is re-textured or repaired, the comparison is made against the governing master, not against a copy.

Does the mold class change the callout?

The callout describes the part, so the mold class does not appear in it. The class still matters, because tool material and expected life decide how well the texture holds over the program. The RFQ is where the two meet. The page on SPI mold classes 101 to 105 shows how to state class and texture scope together so bidders quote the same job.

Where this fits in the texture specification

The drawing callout is the center of the specification. The rest of it is covered in the Mold Texture Standards and design sections of this site:

• The finish systems: VDI 3400, SPI surface finish grades and Mold-Tech textures.
• The processes that produce them: chemical etching and laser texturing.
• A pattern family that needs direction and depth control: leather grain texture.

ASME, ISO, ASTM and VDI documents are cited by number for identification and are not reproduced here; work from the current official editions. Mold-Tech is a trademark of its owner and is named only for identification. Examples are illustrative and do not replace the engineering approval required on your program.