Cot quilts and screen printingH

Have spent most of my spare time this week trying to make silk screen positives if that is the right word with light sensitive emulsion.The first batch had far too much emulsion so had great drips on them ,the 2nd lot stuck to the cardboard underneath so were useless.Knowing how long to burn the image on is a big ? as where can you now buy 250 watt light bulbs thanks to the EU,it is very trial and error but have now got several images which should be use able.It has to be done in a dark room as I have no special light which does not make it any easier.But if anyone knows why a screen subjected to the light source for the same length of time as the others the image doesn't wash out I would be grateful. I made this cot quilt below for some friends of mines granddaughter,they knew it was a girl but did not want all pink
Lo and behold their son and wife is now expecting a child and this material in lime green I had bought from ebay, the grey I had dyed the two looked good together and I was pleased with the cot quilt and I had some small bits left over so made an iPod holder and a camera a case. So now back to grips with the silk screening