Hi GingerJumper
The reasons we tend to put something like an innertube on first are
A--- For extra protection (believe me you can't have enough when you are learning )
B--- If you put gaffer tape straight on the spring it tends to stick permanently and when it gets dammaged it is a nightmare to get off
All you need is an old bicycle innertube cut lengthways and wr***ed round in a spiral overlaping pattern then top it up with tape
Most cycle shops will give you the old punctured ones for free
Jason