IV
As heroin freebase is insoluble, an additional step needs to be taken when prepping it for IV - you need to convert it to a soluble salt. This is an extra opportunity to contaminate your shot so be very careful. Citric or ascorbic acid is commonly used; it is important to use pure powder and not crushed Vitamin C tablets or other acids such as vinegar, as they can contain substances which can cause harm if IV’d and are not sterile. Needle exchanges often give out sachets of citric acid or they are available online.
The citric/ascorbic acid is added when the heroin is in the spoon or (ideally) sterile cooker/stericup and the water has been added. A common mistake is to use too much, leaving an acidic solution which can damage veins. You don’t need to use the whole sachet – just add a little, apply gentle heat and see if it has dissolved. There is an excellent video produced by ExchangeSupplies showing how to add the right amount of acid to your heroin available
here.
Applying heat is not advised when prepping most things as it can lead to poorly soluble cuts dissolving into the shot, but it is usually necessary with heroin freebase to cause it to react with the acid. Try to keep it to a minimum however. Don't forget to take the usual precautions when IVing, use fresh equipment for each shot and keep everything as sterile as possible.
Sterile needles and other IV equipment is available from needle exchanges and many pharmacies across the UK, as well as online.
Insufflating