A head size is not just a head size!
Take for example a hat block made to 22'' oval. Did you know that in that size (as in all sizes) there can be several variations?
On top of 22'' there is slim fit, broad fit...and custom shaped oval as well.
The human head is not a perfect oval. While the majority of heads can accomodate a basic oval hat, because we are all different, one does not fit all. If you take for example, a perfectly fitted hat from your head and put it on a friends head you might fit it just does not sit right. Perhaps the brim buckles where it didn't on you. Why would this be? Because her head may be the same ''size'' in circumference but shorter front to back and wider side to side. This may not matter with softer/floppy hats but will matter when it comes to stiffer ones.
A blocks by design oval 22'' for example, come in 3 shapes. as you can see, the difference is in the front to back and side to side measurements yet all 3 are 22'' circumference.
On top of that, some people had vey odd shaped craniums that may need to be accomodated and measured with a 'conformature' or 'head mapper' (If you can find one).
It looks like some sort of top hat straight out of a steampunk convention! (I WANT ONE!)
Here is a picture of one, borrowed from the below website so you can see one, I recomend having a good read of this site as it is an excellant explanation of the device.
http://houndwelfare.wordpress.com/2009/10/28/houndbloggers-abroad-huntings-historic-clothiers/
So when you are buying a block to suit yourself or a client, to start with you need 3 measurements. (If you are making hats to be bought off the shelf, then you might just go with the basic sizing)
1. circumference
2. front to back
3. Side to side
Then within reason I can select the correct template for the creation of your hat block. Most of the time, a 'slim' or a 'broad' is sufficiant. If the head to fit is very different i may need a diagram and full measurements. These days hat mappers are few and far between so 'close enough may have to be good enough'!
Now, the same carries over to brim blocks and collars as well. A cartwheel brim block for example can be fitted with multiple collars to match crowns. A donut brim block is often (but not always) made to match a crown.
cheers
Darryll
