The reason why you find the top coat brush and activator harden is due to the fact the activator acts to speed up the 'setting' time of the different layers of glazes. This is very frustrating to say the least but there are solutions to ensure that your application goes as smoothly as possible. First, we have a 'Brush Saver' where you can dip the hardened brush in for a few minutes and the solution will restore it to it's former glory. This is the bottle labelled no.5 in your dipping system and usually comes as part of the set in the dipping kits. If you find after many applications the bristle is misshapen and not performing as well, you can always replace it with a spare brush head. This is available in-store and sold as a pack of 10. Handy to have on standby as you never know when that pesky brush plays up!