Straw and Felt Hats are made using the same basic technique, this is called “blocking”. Hat materials can be hand blocked using wooden forms (blocks) or machine blocked using aluminum forms (pans), these are required when using a blocking machine. There is also another type of machine used by hat factories, this is the hydraulic press, necessary for the mass production of hats. Generally the technology employed for making hats has remained the same for many years and could be considered to be “low tech”. All hats are made by hand in even the most up to date factory, all hat making calls for skilled workers and it is a labour intensive craft with anything up to twelve different operations carried out by four different departments before the hat can be delivered to the customer.

Hand Blocking
Is the method used by model milliners and also is the basis of all new shapes when a new metal pan is required. It usually requires two blocks, one for the brim shape and the other for the crown. Before work commences cover both blocks with cling film plastic if you intend to use a stiffening varnish. The straw or felt material is wetted, steamed or both, then quickly pulled over the crown shape, this is secured on the baseline by using a combination of string and drawing pins, then cut off the excess brim material, if you are blocking felt, wait for the felt to cool and the material will stay in shape. A thin coat of felt varnish should be applied to the inside after the felt is dry. If you are working with straw, then wait for the straw to dry then apply millinery straw varnish (two coats of thinned is better than one thick coat) and wait for this to dry completely before removing the shape from the block.

When you are waiting for the crown to dry, start to block the brim, first of all make the head fitting by pulling the brim material over the brim block, then by using string and drawing pins, secure the felt or straw to the raised head fitting part of the block. After you are sure that this is held into place, pull the wetted straw towards the outside edge of the brim and secure with string and/or drawing pins, ensuring that the material is pulled evenly and there are no creases. If you are working with felt then this operation can be quite difficult, much application of steam is necessary to soften the felt during the blocking process, straw is easier. When you are satisfied with the brim shape leave it to dry before applying the varnish. When the varnish has dried the brim and crown shapes are taken off the blocks, trimmed with scissors then sewn together by hand to make the shape.

Millinery wire is hand sewn on the edge of the brim and overlapped, before the petersham edging ribbon is sewn by hand or machine.

The Blocking Machine
Is nothing more than a large press, it is fitted with a foot pedal and hand wheel. The use of this machine is hard physical work, the pans are very hot and steam is produced, great care must be exercised to avoid burns. The pan is manufactured from aluminum and the form has been taken from an original hat made from straw, this original straw hat is filled with casting plaster which when hardened off is then itself hand shaped and smoothed.

The plaster is then used as a three dimensional template for the pan, which is cast using molten aluminum by a sand casting method.

The two parts of the pan are attached to the blocking machine, the top one is fixed to the bridge of the machine and does not move, it is aligned with the lower pan which is attached to the bed which is placed on top of a vertically moving shaft, controlled by the foot pedal.

Heat is applied to the separate pans via two gas burners which allow naked flame to make direct contact with the metal, the pans get very hot, approximately the same as number three on a domestic steam iron. The pre-wetted or steamed hood is then pulled over the male pan. Next the two pans are closed by depressing the foot pedal, which pushes the lower pan upwards towards the fixed upper pan, then the surplus material exposed is pulled outwards and is secured by a cord which is pulled tightly into a “string line” that follows the circumference in the outer rim in one of the pans. Finally the pans are brought together using the hand wheel. This controlled closing, with the outer edge of the hood secured, will put tension on the material as well as defining sharp edges.

Most straws are pre-coated in a stiffening agent or varnish, felt often has stiffener put into it during its manufacture. All types of stiffening agents are designed to soften when exposed to heat and moisture. During the blocking process the material is exposed to steam and pressure, it then conforms to the pan shape, after a few minutes the pan is opened, the cord released from its groove and the hat is taken off the pan. At this time it is soft and stays this way until cooled. The hat shape is now made.

The hat is now passed on to the machining department for the wire to be attached, the wire is pre cut to length and joined with a ferrule or overlapped. It is then dropped into the string line following the outer edge of the brim, this is then sewn all the way round trapping the wire, and the excess hat material is cut off. The binding is sewn on next, then the headband. The machining is done with a specialised millinery machine.

Sewing a three-dimensional object is not as easy as sewing fabric, and much training is required to perfect a good technique.

The Hydraulic Blocking Machine
This is probably the most “high tech” piece of equipment used for hat making. It confirms the shape of a hat after it has already been made on a normal blocking machine and usually after it has been sewn on the edge. The finished hat shape is put into the female pan that sits in the lower part of the machine, a button is pressed and the machine starts its operation, the lower pan is pushed upwards and locks together with the top of the machine. Next, water under pressure is pumped from a reserve tank into a rubber bag (looks itself like a large rubber hat) the bag inflates to the size and shape of the pan, compressing the trapped hat material as it does so.

The intense pressure forces the hat to conform perfectly to the shape of the pan, the hat takes on memory and becomes resilient to damage. One other advantage of the hydraulic operation is that when first blocked by hand, less care and attention is required, as faults or poor definition will be corrected during the process.

It is also possible to press out very simple shapes using this machine only. Although there are a number of advantages in using the hydraulic blocking machine, hats made by this method can look “stamped out”, the straw appears flattened and it can destroy the very texture that many people like about natural straw.