Hat Block – The Workshop Ledger

A hat block, often referred to simply as a block, is a solid form used to shape the crown of a hat during construction or renovation. The felt body is softened with steam and heat, then worked over the block to establish the crown’s size, height, profile, taper, and basic proportions.

What a Hat Block Does

The hat block is one of the fundamental tools of traditional hat making. During blocking, softened felt is stretched and worked over the block and allowed to set around its shape.

A crown block primarily establishes the crown. It does not normally determine the finished shape of the brim, which is worked separately and may be shaped using a brim flange.

The dimensions and profile of the block influence the finished hat, but blocking is only one stage of construction. Subsequent finishing, installation of the sweatband, and final shaping can all affect the hat’s dimensions and appearance.

Open Crown Blocks

Many felt hats are initially blocked on an open crown block rather than on a form representing the final crease.

The resulting open crown can later be hand-shaped into a center dent, teardrop, diamond, telescope, pork pie, or other crease. This allows one block to serve as the foundation for many different finished styles.

Block Size & Head Shape

Hat blocks are produced in different circumferences and head ovals. Selecting an appropriate block involves consideration of both the intended finished hat size and the general shape of the wearer’s head.

A block’s marked or nominal size should not automatically be assumed to equal the final internal circumference of the completed hat. Felt behavior, drying, finishing, sweatband installation, and other factors can influence the finished dimensions of the hat.

The relationship between nominal block size and finished hat size has traditionally been established through workshop experience and varies according to materials, construction methods, and the characteristics of the felt body. Understanding these relationships is an important aspect of hat making and is discussed further within the Hat Making & Construction section of The Workshop Ledger.

Block Shapes & Profiles

Hat blocks of the same circumference can differ considerably in shape and proportion. Crown height, side taper, tip profile, and the transition between the crown and brim all influence the form established during blocking.

A taller or straighter-sided block provides a different starting form than a shorter or more tapered block, even when both are intended for the same finished hat size. The choice of block therefore depends not only on head size, but also on the proportions and style of the hat being made.

An open crown block provides a relatively neutral foundation from which the hatter can create a variety of final crown shapes. More specialized blocks may be designed to establish particular profiles or forms before final shaping.

Block Materials

Traditionally, hat blocks have been made from wood, providing a durable working surface suitable for repeated exposure to the heat, moisture, and mechanical forces involved in blocking.

Modern hatters may also encounter blocks manufactured from materials such as aluminum, engineering plastics, or 3D-printed polymers. These alternatives have made unusual crown profiles, custom sizes, and replacement blocks more accessible while introducing different physical characteristics than those of traditional hardwood blocks.

Because different materials vary in strength, rigidity, heat tolerance, surface hardness, and resistance to moisture, the construction of a hat block may influence its suitability for particular workshop methods. These material characteristics should be understood when comparing traditional blocks with modern reproductions.

Blocks & Brim Flanges

A hat block and a brim flange perform related but different functions. The block establishes the crown, while the flange provides a shaped surface on which the brim can be worked and set.

When a block and flange are used together, the opening in the flange must provide adequate clearance for the blocked crown and the block itself. A flange marked for the same nominal hat size as a block is not necessarily guaranteed to fit, because block dimensions, crown profile, head oval, and flange opening dimensions can vary.

Because block dimensions, crown profiles, head ovals, and flange openings differ among manufacturers and designs, compatibility between individual blocks and flanges should not be assumed. The methods used to evaluate and select compatible equipment are discussed in the Hat Making & Construction section of The Workshop Ledger.

Using a Hat Block

A hat block is employed during the blocking stage of hat construction to establish the fundamental dimensions and profile of the crown. Once the felt has been formed to the block, the resulting crown serves as the foundation for subsequent stages of construction, including brim shaping, fitting, finishing, and final creasing.

The methods used to prepare the felt, secure it to the block, establish the desired shape, and remove the blocked crown vary according to the felt body, the construction of the block, and the hatter’s preferred workshop practices. These procedures are presented in detail within the Hat Making & Construction section of The Workshop Ledger.

Workshop Notes

The Workshop Ledger is currently documenting the use of both traditional and modern hat-making equipment. In 2026, a 61 cm open crown block was 3D printed in PETG with a standard white finish as the workshop’s first primary crown block. The finished block cost $64.13 including shipping; the digital print file was provided at no cost.

The block was printed upright with its flat base on the build plate so that the crown—the working surface of the block—would not require support material or post-processing that might alter its shape. The print was specified at approximately 20% infill, although the final order documentation does not confirm the infill percentage.

Because the block is 3D printed rather than made from traditional wood, its performance will be evaluated through practical use. Particular attention will be given to dimensional accuracy, response to steam and heat, durability, surface wear, interaction with blocking tools, and release of the felt after drying.

The block will also provide an opportunity to document the relationship between nominal block size and finished hat size. With a nominal circumference of 61 cm and an intended finished fit of approximately 60.5 cm, measurements from completed hats can eventually provide practical information about how blocking, drying, finishing, and sweatband installation affect final fit.

These observations will be updated as workshop experience develops.

Selected References

The information presented in this article has been synthesized from historical publications, professional hat-making sources, surviving workshop equipment, and original research conducted by The Workshop Ledger. Ongoing investigation of traditional blocking methods, historical workshop practice, and modern block construction continues to refine and expand the understanding of hat blocks and their central role within felt hat making.

Principal sources informing this article include original research maintained within The Workshop Ledger Research Library concerning hat blocks, open crown blocks, brim flanges, and traditional blocking systems, together with observations of professional workshop practice documented by Hornskov Hat Works. The relationships described between hat blocks, brim flanges, head shape, and crown geometry represent a synthesis of available historical and modern professional sources. As additional primary sources—including historical trade catalogs, patents, manufacturer literature, and workshop manuals—are identified and verified, they will be incorporated into future revisions of this article.