Resin Stiffener

$18.72$102.96 each


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We use millinery stiffener to stiffen hats so they hold their form when blocked or otherwise shaped. There are many types of stiffener you can use. This one is a clear resin often referred to as ‘chemical’ stiffener.

Diluting millinery ‘chemical’ stiffener

Our ‘chemical’ millinery stiffener is quite concentrated. In the past, a rule of thumb was to use it straight on straw hats, including sinamay and parisisal etc. and diluted 50/50 for felt. I recommend using it diluted more than that and rarely use it over 50/50 strength. However, this is personal taste, and some milliners use it straight still.
If you are not sure how much millinery thinner to use, I recommend:
Straw – Straight to 50/50 or 1 part stiffener to one part thinner
Sinamay – 50/50 or 1 part stiffener to one part thinner.
Felt – 1 part stiffener to 3 parts thinner.


Storing and applying your millinery stiffener 

Because of the nature of the solvents in ‘Chemical’ stiffener or thinners, they need to be stored in a suitable container. Many plastics may dissolve if left in contact with stiffener. For this reason, don’t be tempted to store this stiffener in a plastic jar nor use a synthetic brush or you may find yourself with a horrible mess. Your stiffener will come in a metal drum, and you can store it in that, but it will be hard to use from there. I find a glass coffee jar or similar with an airtight lid that my brush can stand up in when I close the lid is perfect. That way I don’t need to soak my brush each time I use the stiffener. I always use a natural bristle brush to apply it.

Work the stiffener into the felt with vigorous motion with a small amount on the brush at a time. Light brushing tends to leave stiffener residue (snail trails) on the felt as does too much stiffener on the brush. Thinned down stiffener will soak in better.

When using straw, you can afford to put more on the brush as long as you work it in well.

when stiffening sinamay, work the stiffener in well with a small amount on the brush to make sure you don’t get ‘windows’. Stiffening before you block ensures there are no stiffener ‘mishaps’ when you take the hat off the block. Stuck cling wrap, shiny inside and clogged up sinamay can all be avoided this way.

Safety precautions for millinery stiffener

‘Chemical’ hat stiffener contains volatile ingredients that are known carcinogens. You must use these stiffeners and thinners with caution.  I recommend using them outdoors and wearing an appropriate respirator. For chemical stiffener and thinner, this is a type A1 or A2 or ‘brown’ filter on a half-face mask. They are readily available and could save your life. Dust masks or even N95 masks will not help.
For more information, feel free to download our MSDS.

Additional information


1L, 4L, 500ml


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