Let's talk about why natural hair brushes bloom. What's normal and how much of a difference should you expect?
Brushes made of natural hairs will change shape over the course of its lifespan. The original shape of the brush when you first receive it in its packaging is not always a good indication of what its actual intended shape is. Fude brushes are hand-bundled and so you may find slight variations from brush to brush because they're made piece by piece but that's not what I mean by the brushes changing shape. In this post I'm going to be talking about 'blooming' which is the process of the hairs opening up in the brush and becoming more fluffy after they're washed.
Think about a natural fibred brush like your own hair in that they react to soap and water in the same way that your own hair does. The hair on your head may frizz when it's dry or it may change texture depending on your age. There's a reason why babies have such soft downy hair but as we get older it'll always be coarser or thicker than a newborn's fuzz.
Fude brushes require a bit more effort to preserve just as we have to work harder to maintain our luscious locks. My post detailing my method of brush cleaning, washing and maintenance can be found here. Synthetic haired brushes won't ever have such a problem because they're made of nylon, taklon or other plastic derivatives which won't warp unless put under extreme heat stress.
New fude brushes are usually packaged in a snug plastic sleeve. It's tempting to pull them out and begin using them immediately but you should always wash them before you use them. Think about it this way — you wouldn't wear new underwear without first washing it because who knows how many people have touched it? We've all seen dozens of people in department stores handling clothes like they're kneading dough in the kitchen. Fude brushes are hand-made so the one brush has passed through multiple sets of hands. Wash them before use!
But, hygiene reasons aside, the main reason why you should wash your brushes before use is that the bristles will loosen from its tight bundling and its condensed packaging into the actual shape of the brush.
It irks to me to see brush reviews online where the user yanks the brush out of its sleeve and starts applying makeup right away. You will not get an accurate indication of how the brush truly performs because the bundling of the hairs will never return to such a packed state ever again. Using an unwashed brush renders the 'review' useless.
How fluffy a brush is will affect the way you use a fude brush. The general rule of thumb is this: the fluffier your brush is, the more diffused your application will be. The airiness of the bristles means that it will pick up less product and the brush is less likely to keep its rigidity. The inverse is true in that the denser a brush is, the more pigmented your makeup will appear. You will pick up more product on a tightly packed brush or one made with more hair.
Here's an example of what I mean. While I own a vast array of fude brushes, it's rare to find doubles in my collection. I purchased a set of Rephr brushes when they first launched but was kindly sent a few by the team so I've ended up with some repeats. I hope putting them side by side will make my point clearer than seeing before and after pictures. Goat hair brushes are the most prone to blooming but they're the most commonly used natural fibre because they're so versatile. Depending on the type of hair, you could see only small changes or the shape of the brush may change dramatically. Although these differences may only manifest in a minute visual manner, you can definitely feel the difference when you run your fingers through the hairs or use the brush on your face.
Here's a comparison of the Rephr #22 bronzing brush from two sides with the unwashed on the left and the washed on the right. You can see that the angle of the brushes changes after it has been washed. It transforms from a tightly packed squarish block to a trapezium. The brush hairs splay out and bloom like a flower opening from a tight bud. It becomes more obvious when you see the side on view as the brush opens dramatically and becomes much larger and fluffier.
You can see how the bristles loosen from the tight bundling within the ferrule after it's been washed. The entire head of the brush opens so the individual hairs aren't stuck so closely together. The end result is that you see more gaps from a top-down view and the brush becomes more airy, fluffy and soft since it is no longer as dense.
Another way to help you discern the difference between an unwashed brush and a washed one is to compare a dry and a wet Beauty Blender. A dry sponge is firm and difficult to use whereas a dampened sponge is softer and more malleable on the face. If you apply your makeup using a brush that's freshly out of the bag, then the brush feels much denser, the bristles may be a little scratchy and the application of product won't be as intended.
How much will a brush bloom?
Determining how much a brush will bloom is dependent on a few factors. Every natural fibre will bloom to differing degrees and the separate grades of hair all react differently to washing. To complicate matters more, the hair quality differs across manufacturers so judging on hair type alone may not tell you how much the brush head will open.
Below are three examples of brushes which appear deceptively similar. From left to right you have the Rephr 05, Hakuhodo J110 and Koyudo BP16. All three brushes were roughly the same size and shape before washing. Post-wash they still look similar when laid flat but when they're turned on their side, you can see the sizeable difference in how much each has bloomed.
The Koyudo BP016 is made of saikoho hair which comes from the chest region on a goat. Saikoho hairs are fine and delicate and it is considered to be the softest, silkiest grade of goat hair (apart from saibikoho which is even softer but is quite rare and expensive). The Hakuhodo J110 is also made from saikoho but mine is not as soft as the Koyudo. The Rephr 05 is made of sokoho which is a grade lower than saikoho. It is still sourced from the chest region of a goat and is comprised of soft, thin hairs.
The brushes above are made of hakutotsuho which is a hair emanating from the shoulder or forefoot area of a goat. These bristles are rougher and thicker than those from the chest region and therefore they're more suitable for use with liquids, creams and hard pressed products because they will pick up more product. Hakutotsuho fibres will only splay out a small bit after washing but they largely keep their original shape.
In my experience, sokoho brushes tend to bloom more consistently than saikoho ones. Some brands produce brushes which don't really bloom while others become really fluffy after washing and continue to become airier after repeated usage. Hakutotsuho hairs don't see as much of a change from their original shape as much as the softer, thinner hair types. I also find that in general, my Koyudo brushes don't tend to bloom dramatically, Hakuhodo brushes show a moderate change, Chikuhodo brushes (particularly from their saikoho range) fluff up quite a bit and Rephr brushes show a moderate to high degree of bloom because they mix their hair grades. Your mileage may vary though given that hairs are grouped and bundled one brush at a time.
What about squirrel hair brushes? There's very little difference between grey and blue squirrel brushes but they don't bloom to a noticeable degree. Squirrel haired brushes will puff up the tiniest amount (if at all) and nowhere near what goat hair brushes will bloom to. The same can be said about Canadian or pine squirrel which remains very soft yet sturdy with very little visible difference in the hairs blooming.
The lesser used horse and sable hairs show almost no change post-wash as well. These bristles are very stiff which makes them good mediums for applying waxy products such as brow pomades or lipsticks so they won't puff up at all.
Controlling the bloom
There's one way of controlling how much a brush will bloom and that's via the use of brush guards. Whether you choose to apply a brush guard to your brush will depend on your personal preference in maintaining a smaller, denser brush head or whether you want a fluffier, airier brush.
I choose to use a brush guard over the majority of my brushes because I have a small face and I like to control exactly where I deposit product. I also like to ensure that foundation brushes such as the Koyudo fu-pa02 (made of hakutotsuho hairs) are tightly packed so that I can easily achieve a medium coverage with my liquid base products. As for my large brushes that I use to apply loose powder, I leave them out to air dry without any restriction so they can bloom as openly as possible in order to diffuse and minimise the amount of powder I use.
Brush guards should be applied immediately after the brushes are washed and can be purchased for a few dollars online. You can also store any unused brushes away in brush guards if you want to maintain its shape.