Monday 11 May 2015

The felt stiffener problem and its solution - an experiment

It seems that one of the best kept secrets ever in millinery is the ingredient of the felt stiffener you can buy. Apart from the fact that it is highly flammable I didn't seem to be able to find out more about what it actually contains (chemically). I also didn't manage to find/buy it in Germany. Highly annoying.

from Alice in Wonderland

So I ordered it from England. Because having to order stuff from England is less than ideal I looked for alternatives and came up with the following experiment to find out whether traditional recipes (easily available ingredients) are as good as "special" stuff (that also happens to be difficult to get).

Here we go

The Hertzwerk - Felt -Stiffener - Project

1. I bought mysterious felt stiffener from England (I am still not quite sure whether they should have really sent that highly flammable stuff via post... but anyway... there is no declaration of contents, I have absolutely no idea, what it is, I assume some sort of resin). That stuff is recommended in Sarah Cant's book "HATS!". She uses that stiffener before she starts shaping the hat. It's said to be waterresistant. (can only be used for felt).

2. The German book "Hut und Putz" by J. Barbe mentions, that most felt cones are treated with some sort of stiffener from the factory and possibly don't need extra stiffener. She does give a recipe (see below) for a shellack based felt stiffener which you can use on untreated felt or to stiffen bowler or top hats entirely (to "superstiff"!) or to give a hat just a little bit of extra "stiff". She refers to the readily available stiffener as "synthetic resin based" stiffeners, that make life a lot easier. She describes how to use the shellack based stiffener after shaping the hat. Shellack based stiffener is also waterresistant. (Shellack-sprit mix in a different concentration can also be used for straw hats to stiffen them and make them shine, as far as I understand the author...)

[Sabine from Kleidung um 1800 brought my attention to Plantago ovata/blond psyllum, or "Indischer Flohsamen" in German. Used mainly for silks but also for millinery purposes (historically). I won't be experimenting with this now, this is just for future reference. It is water-soluable, so it is only suitable for hats that definitely don't get wet (e.g. silk hats on buckram frame)]

The question:

What is better/easier and how do I use it: traditional Shellack stiffener vs modern (resin?) stiffener


Mysterious Felt stiffener from UK (some sort of resin?) (clear)

Shellack based felt stiffener (light yellow)
100gr Shellack flakes (lemon or lighter coloured) +
500ml methylated sprit ("Polierspiritus", it has to contain at least 98% alcohol)
(needs a few days to dissolve, but does this nicely without regular stirring, careful: make sure you use an absolutely airtight container!!)

Picture from book "Hut und Putz" by J. Barbe, p. 217, my shellack mix is lighter yellow than this

 - 2 pieces about A4 size (not hat felt, just ordinary felt) 100 % wool felt fabric (3-4mm thickness, rather soft touch, colour: mottled gray),
- 1 piece A4 size, 100% wool felt fabric (again, ordinary felt) 4mm thickness, rather dense and "stiff", colour: mottled off-white

The experiment:

1. I used one piece of grey felt without any pre-treatment (apart from moisture and steam) and shaped it on the hat blocks, let it dry thoroughly and then applied shellack stiffener inside.

2. I treated one piece of grey  felt before shaping with the mysterious felt stiffener (resin) (one layer) and let it dry. Then I put it on the hat block (on the stand) and used the leftover (too small for any hat block...) on the head to make a headpiece.

3. I applied 3 thin layers of shellack stiffener on the inside and let it dry. The felt was dense anyway and the shellack made it rather stiff. Despite the shellack stiffener being light yellow, you can see there is hardly any discolouration.

white felt with shellack stiffener -  3 layers on inside

(just out of interest I soaked a tiny piece of the grey felt in the shellack - it gets REALLY stiff. And darker and keeps a sort of "wet" look. But I think you could get the felt to a degree of stiffness that would easily hold up a top hat, even though the grey felt was rather soft in the first place)

edit: I've also made a sample on just normal felt to compare directly how stiff you can get stuff. This is more visual. :)

 the result:

While hat-blocking:
I found it really interesing how the felt became sort of fluffy on the surface after heating it (both did, the hair from the felt "stood up"), and of course soft and pliable.

I really liked working with it. 3-4mm thickness is a bit thick, 2-3mm would be easier,I think.
The 4mm piece was not only rather thick but also very densely felted. The shellack stiffener gets soft when heated, so that was not a problem, the thick felt itself was also soft and pliable but the sheer mass of felt is a bit of a hinderance when working with it. The finished hat gets a nice touch from the thickness though, so I couldn't say whether it was a bad idea, or not, to use such thick dense felt.

I am very happy with the hat blocks, they are nice to work with. The water kettle works fine for steam, I just have one word of advice for anyone wanting to do this stuff: steam is REALLY hot. Really really hot. No joke. Be careful.

in the middle of the experiment; front left 2 blocks are w/o stiffener

after drying

I've left the felt dry for 2 days in the loft (that at the moment heats up like a nice sauna due to the weather).
I removed all of the felt pieces from the hat blocks.

All of the felt kept its shape, no matter whether it had been stiffened previously, or not.

Obviously the non-stiffened felt was as soft as it was before, just in a different shape. Wobbly would be another word for it.I then took the shellack stiffener and applied one thin layer inside of the felt hats that had no previous treatment  (if you soak it, it probably wouldn't look nice on the outside), put them back on the block and let them dry. They went a little "crisper" but not hard. I then applied 2 more thin layers of shellack and let it dry again -  they turned out nice and firm. 3 to 4 layers seems to be the right amount for this size.
The shellack leaves a slightly "shiny/sparkly" sort of layer on the felt, but if you brush it with a suede brush it is barely visible.

The felt that I had treated with the resin stiffener was a little stiff, but also qualifies for "wobbly". I think 2-3 layers of resin would have been better. I applied 2 more layers of resin stiffener to the pre-treated felt hat to give it more "crispness", which worked fine.

The felt that I had treated with shellack stiffener was really nice. Not cardboard-stiff but stiff, not wobbly. No shine inside, no discolouration. Very happy with this method.

after taking the felt of the blocks, outside.

after taking the felt of the blocks, inside.

The above mentionned "fluffiness" of the surface gets less while drying, you can iron the felt carefully (I used the iron directly on the felt, maybe a cloth would be a good idea) to smoothen the surface.(NO stiffener on outside!)

After stiffening:

I cut the inside edges even and attached Petersham ribbon (slightly shaped with iron) to the edges. Then I attached a comb. Then decoration. (I will post about the actual hatmaking another time, this post is concentrating on the stiffener)


Both stiffeners work fine.

Personally I prefer shellack, it's got a sort of "traditional" feel to it. I know what's in it, it is a natural product, it's not some sort of mysterious chemical resin (or so...). And it is dead easy to make and comparably cheap AND easily available. The mixture of the above recipe (500ml sprit+ 100gr shellack lemon) will probably last me for... uhm...maybe 100 hats or so...?

I think applying 3-4 thin layers of shellack stiffener and letting it dry thoroughly before hat blocking works fine for the ordinary kind of felt I used. It is a lot easier than applying it after hat blocking, because you can't reach all corners inside as easily anymore after shaping the hat.

So personally, I am going to use that method in the future.

From Alice in Wonderland. Love the stripey socks.


  1. Ein sehr interessantes Gebiet und ich bin schon gespannt auf all die schönen Ergebnisse :)


  2. HI! How did you apply the shellack stiffener? Using a paint brush / paint roller?
    Thank you!

  3. Hi! I used a paint brush and applied several layers as needed.