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The technical sketch, bill of materials, and trim sheet

Covering the technical sketch and bill of materials and trim sheet.

The tech pack for each style number consists of a technical sketch with details, bill of materials and trim sheet, construction specifications, point of measure and size specifications, and supplemental pages for prototype development, labels, folding, and packaging. Let’s examine each of these.

The technical sketch

The technical sketch (also called a flat sketch or flat) is a line drawing of the fashion product.

The design brief may have included an illustration of the garment. From this illustration, a technical sketch is created. The process of creating the technical sketch may start with a hand illustration or may start with a computer-aided design (CAD) or graphic design system. Some designers believe that sketching on a computer stifles their creativity and therefore, they prefer to “think” with pencil in hand.

A hand-drawn sketch of a women's shirt design.

Designer’s hand illustration of a garment.
Technical sketch created using CAD of the same garment.
Two major advantages of using a CAD or graphics system to create design sketches are the time-saving potential and the capability to try out numerous design ideas quickly. To assist the designer, some CAD programs allow the designer to use a pencil-like stylus to simulate the act of drawing. After becoming familiar with the process of sketching by CAD or graphics software, most designers find that the ability to speedily modify a design is a great advantage.
The designer may select a garment sketch from the previous season’s line as a starting point and simply modify design details for the new design for the upcoming line. This procedure greatly speeds up this phase of the design process.
Designs can be created using the following approaches:
  • New garment designs are drawn by using true proportions from a croqui (outlined sketch of a model) stored in the system.
  • Some software programs provide a style library of basic garment silhouettes, such as shirts and pants, as well as garment components, such as collar and pocket styles. The designer creates the new style by bringing the desired components together.
The technical designer translates the final design into a technical sketch to show the details of the garment both front and back. Design details are noted on the sketch or a more detailed drawing is included.
Examples of types of design details that need to be specified include the following:
  • placement and spacing of buttons or pockets
  • any edge stitching or topstitching
  • spacing between pleats or tucks
  • findings, such as the number, size, and style of buttons; zipper length, color, and style; snaps and buckles
  • pocketing, lining fabric, and interfacings.
Design details specified on a technical sketch.
Any information not specified will be decided by the patternmaker or contractor. Thus, it is the designer’s responsibility to specify all garment/product aspects that are important to the look of the design.

Bill of materials and trim sheet

A bill of materials (bill of material or BOM) and trim sheet (listing of all trims to be used) are also included in a tech pack.
Bill of materials for a tech pack.

Although the tech pack and these pages relate to one product, the materials and trims selected may be used in numerous style numbers.

The bill of material and trim sheets are descriptions of the construction components for the product (fabric, thread, trim, linings, labels, hangtags, etc.) including:

  • fiber content
  • weave or knit structure or other material description
  • vendor or supplier
  • placement of trims, labels, hangtags, etc. on the garment
  • width of fabric or size of trim
  • quantity of materials and trims
  • cost.

Having covered the technical sketch and bill of materials and trim sheet, let’s move on to the next part of the technical pack.

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Product Design and Manufacturing Processes in the Fashion Industry

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