[sdiy] Photo etch experience please

[Joe]

Hi all, I am trying to use photo sensitized boards and make circuit
boards. I have good enough luck using the sun as my light source but now
I want to do this in the house so I am independent of the weather. Using
a 13w csf bulb I have to expose for 22 mins! That is 4 times what people
show on their tutorials? Does anyone else have experience to share with
this?
 Outside with sunlight my exposure is generally 14 mins. Again is anyone
else on the list able to share any experience with this. Thanks Joe.