I often get asked what the difference is between the nozzles supplied with the DA Applicators and which one is the best to use, so here is a quick overview:-   The fan jet nozzle has a 25 degree spray pattern and works with a back pack and larger pumps too.  I use this for conservatory roofs, UPVC, guttering and fascias and I find the applicator is a much easier way to quickly apply chemicals for pre treatment.   My favourite go to product is 2 cap full’s of Virosol (cleaner and degreaser) in a 20 litre back pack.  Once applied I go and have a quick cuppa and let the chemicals go to work, when I come back I find it is much easier to agitate the dirt with a brush and rinse off.   Sometimes if there is a lot of dirt to remove then I will use 2 cap full’s of traffic film remover.  It is advisable to apply this to a wet surface and then rinse straight away as I have heard of TFR staining UPVC if left on for too long.  It isn’t advisable to use TFR when it is hot or in direct sunlight.  I am also currently experimenting with various products designed specifically for glass and UPVC so I will let you know how I get on with these and if I can recommend any of them.   The full cone nozzles are recommended if you intend to use Soft washing chemicals such as Sodium Hypochlorite and Biocides.  The kit comes with two full cone nozzles:- The purple ref No 6.5 nozzle has an orifice size of 2.4mm with a 50 degree cone shaped spray pattern The dark green ref No 10 nozzle has an orifice size of 2.8mm with a 70 degree cone shaped spray pattern.   The ref number refers to the size of the orifice, so the smaller the ref number the smaller the orifice.  Reducing the size of the orifice affects the flow rate and this is often described like putting your finger over the end of the hosepipe, you reduce the flow but get more velocity.   This is why the purple 6.5 nozzle will work fine with a back pack but the dark green No 10 nozzle won’t.  The dark green nozzle needs a higher flow rate and requires a pump which produces 5.3 litres or more to work well whereas backpack pumps tend to only be 3 to 4 litres per minute.   The full cone nozzles don’t generate excessive spray drift but this is an important factor to consider as you will need to protect nearby plants, lawns and neighbours property and of course yourself!   Some chemical suppliers will also recommend which nozzle is best to use with their products.   We also have a short video demonstrating the difference between the spray patterns; please click on the link to view. https://www.youtube.com/watch?v=pDF1KgvkOLk   Hope this helps.