Cock I agree, but I have a niggle. I think for 99% of rats there are much much better options than hardwood shavings, which can cause respiratory issues and should not be used for small animals under normal circumstances, as I'm sure you know, but putting it out there in case others read the thread:
Softwood shavings can cause issues in small animals due to the phenols in the oils. Rats especially because they are prone to respiratory issues. Cedar and pine are the main ones you need to watch out for, though other softwoods are an issue too. Hardwoods are safe, but it is extremely difficult to get hardwood shavings in the UK.
There is some debate about the pine used in UK shavings contain less phenols than those in the US (where most of this research has taken place) so is therefore not as much of a risk, along with the fact that most of the major brands heat treat the shavings in the UK, which burns off a significant amount of the phenols (but not all by any means!). But it's not a risk that you want to take if you can avoid it by using another bedding which is just as economical, such as aubiose, megazorb, premierbed, finacard, etc. There is actually a new corn-based product available which looks great, but only one shop I know sells it and they never have it in stock.
Some people use wood shavings anyway. A lot use them because it's not common knowledge and it's not something that you really think to research when you're buying your first pair of rats, and some use them because they don't think it's too much of a risk. Personally I'd say it's not worth the risk, but then I'm one of those who takes the rat to the vet at the slightest sniffle to have their lungs checked!
However, our boys are in [heat treated & dust extracted] shavings. It's the lesser of two evils as, between the two of them, they've reacted badly to every other major bedding available, even carefresh after a couple of months in it with no issues. We switched to newspaper which was okay but wasn't absorbent enough, so we were having to clean their cage out/mop up puddles multiple times a day. One of my boys will have lifelong respiratory issues thanks to the use of megazorb and premier bed in his early days with us. Shavings are a very temporary solution and not a decision we took lightly, one we consulted our very good vet and our brilliant local breeder on too as we couldn't leave them in a bare cage. Ironically, wood shavings are the only thing that don't have either one of the boys constantly sneezing at the moment. But DO NOT use them unless you're really backed into a corner and do not use them unless you talk to your vet first.
Our girls were perfectly fine in other substrates until they started shoving it down the back of their new cage buggers and having allergy-prone rats is not very common at all, so please don't let that put anybody off.
Our boys will be out of shavings by the end of the month thankfully, as we'll be buying their new cage (American-style, so fleece is attachable unlike tray styles) when pay day rolls around!