I personally make my solution as strong as possible (350ml-500ml to a gallon), but for the recommended dose I think it is 100ml-250ml to 1 Gallon of water as there are different health and safety issues with this sort of thing you will have to look into this yourself if you work for yourself then it is up to you but be careful when applying I usually use a pair of rubber gloves and watch your eyes for splashes I use goggles once you have applied rinse off. There is also a strong smell from ammonia but I give the customer plenty of warning and they seem fine by it I have had no come backs I have also used on stain glass windows (use a weaker solution) and the results are very good as amonia does not seem to streak like as when using washing liquids and polishes up quite well.
Also works wonders on alloy wheels
Hope this helps. Alan