Blocked Foundations
for Covered Hats

Blocked foundations for fabric covered hats using wooden blocks

Fabric covered hats, using a blocked canvas foundation allows the use of any shape that can be achieved with felts and straws. The techniques used for blocking the canvas foundation is not unlike when blocking straws and felts, however, the procedure involves added tasks because once blocked, the foundation needs a covering, which could be of any type of fabric or material.

The millinery tools required to achieve this blocking technique can vary, and in this exercise, I am instructing in the use of wooden blocks. However, hot blocks are available for crowns shapes, which I find much more user friendly than the blocked foundations worked on wooden ones. My reasons are

(a) ease of use,

(b) speed of drying.

Brims are all shaped on wooden brim blocks, using water to wet the canvas/net ready to stretch over the block, to form the blocked foundation and allowed to dry. Natural drying could take up to 24hrs, depending on the weather, whereas a drying cabinet should only take up to 2hrs. It is ESSENTIAL that the canvas is ABSOLUTELY DRY before removing it from the block, otherwise it will crumple immediately it is removed.

Two important hints when forming blocked foundations on a wooden hat block are:

1. The procedure should not be rushed.

2. Have access to the block at all times while being worked on.

Some brim blocks have a hole in the centre allowing the canvas to be cut in the centre, snipped into the turn of the brim and pinned securely into the hole. making a seam allowance for attaching to the crown.

Alternatively, the brim blocks with the added 'collar' section, which is the oval shape of the crown and attaches to the flatter brim blocks to allow for crown placing. The foundation canvas can be wired at that point, and the depth of the "collar" will form the seam allowance. The canvas is pulled, as tautly as possible over the block and secured with drawing pins around the edge, making sure that the pins are well past where the edge of the brim is to finish. Note: Elastic or cotton tape secured under the drawing pins can improve the ease of blocking and avoid the pin marks on the canvas.

Step by step Brim Blocked foundations:

1. Block the foundation Canvas etc on the desired brim block shape.

2. If the brim block has a head shape, cut the shape to fit, leaving seam allowance.

3. If the brim block is flat,insert the correct sized "collar",to determine the crown placement, and place a temporary head wire at the join of the collar and block, which will also be the position where the crown will be sewn, and insert a seam allowance for joining the brim and crown.

4. Allow the brim blocked foundation to dry, and remove from the block.

5. Stitch a wire around the edge of the brim. Allow enough length in the wire to enable the brim to slide over the block for reblocking. Substantial overlap is required, 15cm at least, and the larger the brim, the longer the overlap.

6. Secure the headwire. Stiffen the dry blocked foundation with Hat Stiffener.

7. Cut the head shape from inside the headwire, leaving a seam allowance. 1.5cm.

If the wooden brim block is one with a collar ( a shallow oval shape on the top of the block) stretch the canvas over the collar and secure a wire closely to the bottom of the oval collar. Cut the section of canvas blocked foundation at the top of the collar and trim to allow for seam allowance. You should now have a perfectly blocked foundation for your brim.


Once the brim and crown blocked foundations are wired it is necessary to coat each shape with sizing (stiffening). Usually it only requires one coat, but if the heavier fabrics are used, extra coats will improve its durability, but be mindful that it will also add weight.


At this stage, you can see the results of your work. Throughout all the process of building the blocked foundation it is essential to keep everything in good shape in order to create a smooth and well shaped hat.

The brim and crown are still separated when applying the fabric covering. This enables a neater finish as most of the raw edges are directed to the head wire and can be camouflaged by the lining and petersham head band.

Some fabrics tend to show the weave of the canvas or netting when pressed. We purposely choose fine fabric to keep the weight to a minimum, so an underlining is inserted the problem is eradicated to ensure that any pressing marks are avoided.

In choosing an underlining, it needs to be soft and stretchy so that its existence is virtually undetected on completion of the hat. A fine Pellon or felt, which can be stretched over the wooden block before covering the blocked foundation, is perfect for the job. White is best to use so that any color doesn't reflect through the finishing fabric.

Once the underlining is attached the fabric can be stretched or draped to form whatever finish is required.

If the brim has curved shaping it may be necessary to block the covering fabric. A straight drooped brim may not need this blocking.

8. Cover the brim block with fine plastic to avoid soiling any fashion fabrics.

9, Stretch the chosen fabric over the block and secure with drawing pins, (The fabric can be wet or steamed to form a better shape).

A curved brim will require the under covering to be adhered to the underside of the brim foundation to avoid it from dropping down from a down-turned brim or the reverse if it is an up-turned brim.

10. Using a glue, secure each layer to avoid the fabric dropping out of a down turned brim etc. (The glue could be an aerosol spray, a powder glue, a stainless such as 450 Stainless Adhesive or Vliesofix).

11. If the fashion fabric is not very thick place a fine Pellon or craft felt between the fabric and the foundation.

12. If the interlining is required repeat the gluing process.

13. When all the under layers are in position, return the brim to the block and press well with a hot iron to achieve the best adhesion. but DO NOT USE STEAM.

14. Cut the centre from the fabrics leaving a seam allowance in the same manner as with the foundation canvas.

15. Replace the brim back on the block and repeat the stretching and gluing process to cover the upper side of the brim.

16. Depending on the finish required, complete the brim edge, and cut the upper centre fabric away.

17.. On completion the crown and brim can be secured together with a back stitch (see samples). Any trim is then applied.

THE CROWN with a flat tip or sharp turn

The same procedure occurs to block a crown using a wooden block. Refer to hot blocking to block a crown using the hot method.The covering fabric is applied as follows:

1. Glue underlining to the tip and stretch the covering fabric over the tip.

2. Pin securely and then backstitch approx 1cm below the turn.

3. Trim the seam allowance to the backstitches so that NO seam allowance is left.

4. Place underlining from the fabric overlap to the head wire. Then sew the band fabric to the edge (inside out and upside down).

5. Glue a second layer of underlining to cover to the tip edge, the pull the fabric down and secure with backstitch to the seam allowance of the crown.


This technique creates a smooth rounded crown with a band as it's finish.

1. Block the foundation canvas on the correct sized domed block.

2. Block the underlining in the same manner and glue to the foundation.

3. Block the fabric in the same manner to take on the dome shape.

4. Pin securely, pulling the fabric to a smooth finish and then backstitch as low as possible without creating any creases. Depending on what fabric is used, the band should finish up to be approx. 1" to 1 1/2" wide.

5. Trim the seam allowance to the backstitches so that NO seam allowance is left.

4. Sew the band fabric to the edge (inside out and upside down). Making sure this stitch line is above the last.

5. Glue a second layer of underlining to cover the stitch line, then pull the fabric down and secure with backstitch to the seam allowance of the crown.


1. Remove the temporary wire from the crown and place the crown onto the brim.

2. Pin the seam allowance together making sure there is no obvious easing at any area.

3. Backstitch to secure.

4. Place the hat onto a hot block to fit the size of the hat.5. Decorate the hat to your choosing.

6. Pin a Petersham band into the pressed hat to determine the length of the band.

7. Remove the Petersham and stitch the ends together.

8. Block a prepared lining to the size of the hat and place this inside the crown to measure the length of the lining.

9. Cut the lining and place the Petersham band on to the edge of the lining, and stitch by machine, using a small stitch to allow each stitch to penetrate each of the rib turns of the Petersham.

10. Hand stitch the Petersham (lining attached) to the headline of the crown.

11. Re-block the hat to complete.

For more informations on what is required for covered hats, click here Blocked foundations