How to clean a problem / climb?

first of all, good effort! it depends on the type of rock whether you need to take extra special care with brushing. sandstone, especially in moist conditions, damages a lot faster than granite, for example. in my experience, a stiff hair or plastic brush is enough for most moss and lichen, after plucking as much as you can off by hand. only when stuff stays on, gently use the wire brush. maybe something like a cheap wirehanger to get crud out of cracks and corners? good luck!

I am in the same situation right now. I only have a stiff hair brush but today it failed me for the first time on some moss that just would not come off. I might have to get another one thats a little stiffer for more durable dirt. But so far the hair brush did a really good job for me.I would advice you on getting a few differnt sizes of brushes though because mine is a little to big for narrow cracks and a little to small to get the big jobs done fast.Maybe also get some kind of extension so you can clean spots that are higher up easier. I hope your having as much fun as i am cleaning and climbing the "neighbourhood" boulders. If you have any advice for me i would like to have that as well. Since im also fairly new to cleaning rocks :)

Good morning, as mentioned before it depends on the type of rock and the amount of mud, moss and dirt which is situated on the boulder. For example for vulcanic type of rock or granite you can use a wire brush this makes no damage to the rock, for sandstones or other "softer" rocks, wire brushes are an absolutely no go! You will brush new holds in the surface! In sandstone, try with several hair or plastic brushes, begin with the softer and go further to the harder, until you reach the point where it works best and makes not or less damage to the rock surface. On Limestone you have to see how hard the limstone is, on dolomite wire brushes are (by my experience) often to hard. If there are rests of mud or dust use some water, or wait after the next rain, this will wash the rest dust from the hold. Cheers Hartwig