Blocking Fundamentals

BLOCKING FUNDAMENTALS

A note before you start

Blocking is where millinery begins to make sense.

It is also where many milliners lose confidence early on. Materials feel unfamiliar, shapes feel difficult to control and it can be unclear how much pressure to apply or when to stop.

Blocking is not about force or perfection. It is about learning how materials respond and working with them rather than against them.

This understanding comes through handling, not rushing.

What blocking actually is

Blocking is the process of shaping a material over a form using moisture, heat and controlled pressure.

The block provides the shape, but it is your hands that guide the material into place.

It is not simply pulling material over a block. It is a conversation between the material, the block and your hands.

Preparing your block

Before you begin blocking, lightly mist your block with a water spray bottle and then wrap it in Glad Wrap. This helps prevent materials from sticking during the drying process, particularly when using stiffeners.

Press and Seal is a popular option and works well for single-piece blocks. However, it is not recommended for puzzle blocks as it can hold the pieces too tightly together, making them more difficult to separate during removal.

If using puzzle blocks, take a moment to pull them apart and check that all sections move smoothly before you begin. A light sprinkle of talcum powder can help the pieces slide more easily and prevent sticking.

The role of steam and moisture

Steam and moisture soften fibres, making them flexible and responsive. Different materials respond in different ways - for me, this process is essential when blocking straw.

Wet, steam and shape into the block first, allowing the material to take shape before introducing stiffener.

Once blocked, the material should be allowed to dry fully - either naturally (or with the help of a hair dryer). Only once it’s fully dried on the block should an iron be used to refine and set the shape further if needed.

Put the stiffener on the straw after the form has been established, not before.

Some materials require a slightly different approach.

Paper straw is pre-stiffened with a diluted PVA mixture before blocking, allowing it to hold shape more effectively as it is worked.

Vintage straws require a lighter hand with moisture. Using less water helps prevent damage, and applying stiffener to the inside of the material before blocking can help retain the natural sheen of the straw.

Pressure and tension

One of the most difficult parts of blocking is understanding how much pressure to apply.

Too little pressure and the material will not take shape. Too much and it will distort, crease or resist.

The goal is controlled tension, not force.

Your hands are the primary tool in this process.

The warmth of your hands helps ease the material into shape, allowing you to guide it gradually and with control.

Learning to use your hands effectively will give you more sensitivity and accuracy than relying on force alone.

The type of blocking pins you use can also make a difference. I prefer Guy Morse Brown blocking pins as they are easier on the hands when inserting into wooden blocks. It is also helpful to keep a small pair of pliers nearby to assist with removing pins cleanly and safely.

Using tools to support the process

Ropes, elastic, calico and other tools are often used to help hold material in place while it dries.

They are a valuable part of the blocking process, particularly with certain shapes or more complex blocks where consistent tension is needed.

However, these tools are there to support the work, not replace it.

The shape itself should be established through your hands first - through controlled pressure, careful placement and an understanding of how the material responds.

Once the material is sitting correctly on the block, tools can then be used to hold that shape securely while it sets.

Relying on tools to force a shape too early can lead to uneven tension or distortion. Used at the right stage, they help maintain a clean and consistent result.

How materials behave

Different materials respond in different ways.

Straw responds best to a gentle, gradual approach. It should be encouraged into shape, not forced too quickly. That said, some blocks require a degree of stretch or shrink to achieve the desired result. This should be done carefully and progressively.

Felt allows for a firmer approach. It is more forgiving and can withstand more direct pressure during blocking. Felt is generally stiffened before it is placed on the block.

Paper straw behaves differently again and benefits from being stiffened before blocking to support its structure during shaping.

Other structural materials such as sinamay and buckram each have their own behaviour, but all respond to the same principles of moisture, heat and controlled pressure.

Understanding both the differences in behaviour and the shared principles is key to working confidently.

What you are aiming for

A well-blocked piece should feel smooth, even and intentional.

The material should sit cleanly against the block, with no unnecessary tension, bubbling or distortion.

The shape should be achieved through blocking itself, not corrected later.

Common blocking mistakes

Forcing the material too quickly
This often leads to distortion, cracking (in straw), or uneven shaping.

Relying too heavily on tools
Ropes, elastic and other aids are helpful, but they do not replace hand control.

Not removing creases before stiffening
All creases and bumps should be resolved during blocking. While it is sometimes said they can be worked out later, this often leads to more work and a less refined finish. A clean block leads to a sharper result.

Rushing the drying stage
Materials need time to fully settle into shape on the block. Even if the surface feels dry, moisture can still be held deeper within the material. Using a hair dryer can help speed the process, but it does not always dry the material all the way through. I recommend leaving the piece on the block overnight to ensure it has properly set.

Using too much moisture on delicate materials
Vintage straws in particular require restraint. Excess moisture can weaken fibres and reduce surface finish.

Removing the material from the block too early
Taking the material off the block too soon can undo the shape you have just created. Even slight movement at this stage can introduce distortion or softening of edges. Always allow the material to fully dry and set before attempting removal.

A simple starting approach

If you are working with straw:
Wet, steam and block first.
Use your hands, along with ropes or elastic where needed, to guide the material into shape.
Allow it to dry completely.
Refine the shape with heat if required.
Then apply stiffener in controlled sections.

If you are working with felt:
Apply stiffener first, then steam.
Block using firm, controlled pressure.
Felt benefits from consistent steam while shaping, so a small handheld steamer is very useful for applying steam exactly where you need it while you work.

Felt is generally more forgiving than straw, but still benefits from controlled pressure and patience during blocking.

If a blocked piece is difficult to remove once dry, a small amount of heat from a hair dryer can help ease it away from the block. This should be done slowly and gently to avoid distorting the shape.

Keeping the process simple will help you understand what each stage is doing.

Finishing notes

Some materials benefit from small finishing adjustments.

If a straw piece loses some of its natural sheen during blocking, a very light spray of hairspray can be used to restore a soft, low sheen to the surface.

Not all materials require stiffening. Fabrics used as overlays on structured foundations are often secured through stitching alone, relying on the base material for support.

Hat blocks should be cared for after each use. Avoid leaving them damp, as moisture can affect the timber over time. Wipe blocks gently with a slightly damp cloth if needed, then dry thoroughly before storing. Always remove Glad Wrap after blocking, as colour transfer can occur if it is left on the block and moisture can build up underneath on the surface of the timber.

A final note

Blocking is a skill that develops through repetition and observation. The more you work with materials, the more you will recognise how they want to move, where they resist and how to guide them into shape.

When starting out, a single, well-chosen crown block can be used to create a wide variety of shapes. Learning how to adapt one block will teach you far more than collecting many shapes too early. At The Millinery Retreat, access to over 700 hat blocks allows you to explore a wide range of shapes before deciding what you truly need.

If you are working gently, gradually and with attention, you are doing it exactly right.
Your hands are your most important tool.

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