Mold-Tech Textures: Series, Draft Angle and How It Works

Mold-Tech is a proprietary texture system from Standex Engraving, not a public numeric standard like SPI or VDI 3400. Instead of a roughness scale, it is a library of texture patterns identified by numbers such as MT-11000, which reproduce grains, leathers, wood, and geometric designs on molded parts. It is the dominant texture language of the automotive industry. Because it is pattern-based rather than roughness-based, Mold-Tech has no official conversion to SPI or VDI 3400, and its key design driver is texture depth, which sets the required draft angle. This page explains how the system works, how patterns are organized and specified, the draft rules, how the textures are made, and how Mold-Tech compares with the numeric standards.

What is Mold-Tech?

Mold-Tech is a texturing system developed and maintained by Standex Engraving, a global supplier of mold texturing services and part of Standex International. Unlike SPI, which describes polish, or VDI 3400, which describes roughness on a numeric scale, Mold-Tech is a catalog of specific texture patterns. Each pattern has a serialized identifier and a defined character, from fine grains to deep, complex reliefs, and is reproduced on the mold cavity so that it transfers to the molded plastic part.

This distinction matters. A numeric standard answers the question "how rough or how smooth" with a single value. Mold-Tech answers a different question: "which exact pattern." Two parts could share a similar average roughness yet carry entirely different Mold-Tech patterns, because the pattern, the visual and tactile design, is the point. This is why Mold-Tech dominates applications where appearance identity matters, especially automotive interiors, where a precise grain is part of the product.

Why Mold-Tech is proprietary, and why that matters

Mold-Tech is owned and maintained by Standex, which means the patterns are a proprietary library rather than an open published standard. In practice, this has three consequences for anyone specifying it. First, the authoritative reference is the Standex sample set, not a public table; a Mold-Tech callout points to a physical pattern plaque. Second, an MT number reproduced by a shop other than Standex is a copy, which may differ subtly from the original, so for parts with strict appearance requirements the original is worth the premium. Third, because the library is proprietary, cross-references to SPI or VDI are always approximate and unofficial.

The reliable way to treat Mold-Tech is therefore to anchor on the physical sample and the Standex specification for the chosen pattern, and to treat any roughness equivalence as a rough guide only. This is the same principle that applies across mold texture standards: the physical reference wins over the chart.

How Mold-Tech patterns are organized and specified

The full library contains a very large number of individual patterns, each with its own MT number. Reference charts commonly group them into families that move from fine and shallow to deep and complex, but the grouping is a mental map, not part of the specification. What a drawing actually needs is the exact pattern, its depth, and its gloss.

Texture family	Typical character	Relative depth	Typical use
Fine grains and stipples	Low relief, subtle texture	Shallow	Visible housings, surfaces close to gloss
Medium grains and leathers	Moderate, tactile grain	Moderate	Automotive interiors, appliances, consumer products
Coarse grains and industrial patterns	Pronounced texture for grip and durability	Deeper	Tool housings, equipment casings, high-contact surfaces
Deep and geometric reliefs	High relief, complex or 3D patterns	Deepest	Premium visual effects, strong tactile identity

A complete Mold-Tech callout on a drawing typically includes the MT pattern number, the texture depth, the gloss target, and the surfaces it applies to. Writing the depth next to the pattern number matters, because the depth is what sets the draft.

Texture depth and the draft angle rule

The single most important engineering relationship in Mold-Tech is between texture depth and draft angle. A textured sidewall must have enough draft for the part to pull away from the pattern cleanly; with too little draft the texture drags, scuffs, or scratches the part during ejection, ruining the appearance and often forcing expensive tooling rework.

The widely used rule of thumb is to add about 1.5 degrees of draft for every 0.001 inch (0.025 mm) of texture depth on sidewalls, with some suppliers recommending up to 2 degrees for demanding resins and tall walls. Because deeper patterns require more draft, the texture choice is never purely cosmetic; it constrains the part geometry and should be decided together with the draft strategy at the design stage.

Texture depth	Typical texture	Minimum added draft (at 1.5° per 0.001″)
0.001″ (0.025 mm)	Fine grain	1.5°
0.002″ (0.05 mm)	Medium grain	3.0°
0.003″ (0.075 mm)	Coarse grain	4.5°
0.005″ (0.125 mm)	Heavy leather	7.5°
0.007″ (0.175 mm)	Deep wood or hide	10.5°

Approximate guidance for shrink-away sidewalls, added on top of the base draft. Confirm the exact requirement for the chosen pattern and resin with the texture supplier. For the full method, see draft angle by texture.

The shrink-away versus shrink-on distinction

A critical detail that separates experienced specifiers from beginners is that the standard draft rule applies only to shrink-away sidewalls, surfaces where the plastic shrinks away from the steel as it cools, naturally creating clearance. Surfaces where the part shrinks onto the steel, gripping the core, behave very differently and require approximately three times the draft of the shrink-away rule.

Surface condition	What happens on cooling	Draft requirement
Shrink-away (cavity side)	Plastic pulls away from the steel	Standard rule, about 1.5° per 0.001″ of depth
Shrink-on (core side)	Plastic clamps onto the textured steel	About three times the standard rule
Lifters and slides	Release depends on the direction of action	Evaluated relative to the movement, not only the parting line
Textured shut-offs	Steel slides against the texture at closing	Extra draft or special engineering

A part cooling onto a textured core clamps down on the pattern, and without substantial extra draft it cannot release without dragging across the texture. Missing this distinction is one of the most common and most costly texturing mistakes, because by the time it shows up, the steel is already cut.

How Mold-Tech textures are made

Mold-Tech patterns are produced mainly by chemical etching. A mask carrying the pattern is applied to the mold steel, and acid selectively etches the exposed areas to a controlled depth, transferring the design into the cavity surface. Etch depth is governed by the acid, the exposure, and the number of etching passes, and it determines both the visual depth of the grain and the draft the part will need.

For complex 3D geometry, digital reproduction, and patterns that cannot be masked evenly, many patterns are also produced by laser texturing, which cuts the pattern from a digital file. After either process, the final gloss is commonly set by a light blasting pass checked against the master sample.

These pattern-making processes suit organic grains, leathers, woods, and fine geometric designs that would be difficult to produce by the EDM process used for VDI textures or by the mechanical polishing used for SPI. This is the technical reason Mold-Tech occupies the "pattern" niche while VDI occupies "roughness" and SPI occupies "polish."

The material changes the result

As with every mold texture standard, the molded polymer affects how a Mold-Tech pattern appears and how much draft it needs. Different resins do not behave the same on the same texture: a PA (polyamide) and an ABS molded in the same textured cavity can require different draft angles and can render the pattern with different sharpness. Semi-crystalline materials, which shrink more, tend to grip a textured core harder, pushing toward the shrink-on draft territory and demanding extra clearance. Glass-filled grades raise surface roughness and can blunt fine patterns. The practical rule is to confirm the draft and the appearance for the specific resin, not for texture in the abstract.

Mold-Tech compared to SPI and VDI 3400

Mold-Tech is one of three dominant mold texture references, and the cleanest way to separate them is by what each describes.

Factor	Mold-Tech	SPI	VDI 3400
Type	Proprietary pattern library	Public polish standard	Public roughness standard
Owner	Standex Engraving	Plastics Industry Association (formerly SPI)	Verein Deutscher Ingenieure
Describes	Which pattern	How smooth, by finishing method	How rough, by Ra-based number
Specified by	MT number, depth, gloss	Grade A-1 to D-3	Grade VDI 12 to VDI 45
Main process	Chemical etching, laser	Polishing and blasting	EDM
Typical market	Automotive interiors, appliances	North American molding	Europe and worldwide

There is no official conversion among them. A Mold-Tech pattern can be loosely associated with an approximate roughness, and therefore loosely with a VDI grade or SPI range, but the association is unofficial and should always be confirmed against a physical sample. For the detailed cross-reference, see the SPI to VDI 3400 to Mold-Tech conversion page and the overview on the mold texture standards hub.

Frequently asked questions

What is Mold-Tech?
A proprietary texture system from Standex Engraving: a library of texture patterns identified by MT numbers, produced mainly by chemical etching and widely used in automotive interiors.

Is Mold-Tech a numeric standard like VDI 3400?
No. SPI and VDI 3400 are scales of smoothness and roughness. Mold-Tech is a catalog of specific patterns; it answers "which pattern," not "how rough."

How do I specify a Mold-Tech texture on a drawing?
State the MT pattern number, the texture depth, the gloss target, and the surfaces it applies to, and approve it against a physical sample plaque.

How much draft does a Mold-Tech texture need?
About 1.5 degrees per 0.001 inch of texture depth on shrink-away sidewalls, added on top of the base draft. Surfaces that shrink onto the steel need roughly three times as much.

What is the shrink-away versus shrink-on difference?
Shrink-away surfaces pull away from the steel as they cool and follow the standard draft rule. Shrink-on surfaces grip the core and need about three times more draft to release cleanly.

How are Mold-Tech textures produced?
Mainly by chemical etching through a pattern mask, with laser texturing used for complex geometry and digital reproduction, and a light blast to set the final gloss.

Does Mold-Tech convert to SPI or VDI 3400?
Not officially. Any equivalence is approximate, based on matching roughness, and should be confirmed with a physical sample.

Why choose the original Mold-Tech over a copy?
A copy of an MT pattern may differ subtly from the Standex original. For parts with strict appearance requirements, the original ensures the exact, repeatable grain.

Normative References & Sources

• Standex Engraving Mold-Tech, texture library and technical guidance: standex.com
• ISO 1302, indication of surface texture in technical product documentation: iso.org
• Verein Deutscher Ingenieure (VDI), VDI 3400 guideline: vdi.de
• Plastics Industry Association (formerly SPI): plasticsindustry.org

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Reviewed by Marcel Dias, Technical Editor. Mold-Tech is a trademark of Standex. Pattern, depth, and draft values are provided for reference and are approximate; verify against the original Standex specification and a physical sample before production. See our Disclaimer.