Concentrated PCB developer is a mixture totally free from sodium hydroxide. 500g pack makes up into 10 ltr of solution with water. The 1 litre Liquid Concentrate Developer makes up 10 litres of working developer solution, completely free from Sodium Hydroxide. A board may be left immersed up to 50 times longer than the normal 20/30 seconds developing time without risk of undercutting or thinning the photoresist. It will develop all positive working photoresists as well as aqueous dry film laminates, and has a life of several months in a processing tank.