Even an high-quality brush can over time lose the original shape of the tip due to frequent use and cleaning.
There are many forums on the subject, which recommend washing the brush with hot water, even if with natural fibre this step would involve an acceleration of the deformation process; you can even find the ancient custom (suggested by many artists) of sucking the brush tip and use saliva to change its shape.
The only important thing is proper cleaning and care: first choose a suitable soap which keeps the fibre elastic and hydrated, avoiding too aggressive detergents.
Rub them only on special silicone mats and above all do not let them dry with the tips resting, but facing upwards. Do you know a little trick to keep the tip we have chosen intact?
After having thoroughly cleaned them and when they are still wet, apply the special vegetable soap with the fingers on the tip of the brushes to perfectly restore the original shape until the next use.
And it is an excellent protection for storing them in the boxes!