Buy a quantity of potassium bromide, and dissolve it to make a 10% stock solution. It tends to clump ot form a fused solid; a mortar and pestle or a pair of pliers and a zip lock bag are useful tools to break up the larger lumps. You may be able to find it at a pool/spa supply house, if no photochem retailer/online seller is accessable to you. 500mL of a 10% solution; i.e 50g of K Br lasts me quite a while; I would guess I mix it at an nterval about every 1-2 years, and then use it as the source of bromide in all the developers that I scratch mix.
10% K Br can be added to the standard multigrade developer in the tray, a bit at a time to warm the image tone.
Most develpers like Dektol/D72 have bromide in them at a rate of 1-1.5g/l of stock. Warm tone developers use 4-6g/l of bromide per litre of stock.
Dektol is usally used diluted 1:1 to 1:3.
Ilford MG is a highly concentrated stock; I recall it is used diluted 1:9
Once the MG developed has been diluted, try up to about 30mLper litre of working strength developer of 10% bromide solution to warm things up. Once you add too much, images take forever to develop, like 4minutes, and a lot more exposure.
Bromide is technically a restrainer, so you will need more exposure/ a longer period in the developer to get the same image tones as prior to adding the bromide. You will most certianly get a warmer image tone. I usallu develop for 2', develoiper at about 20C, and tweak exposure after boosting the bromide level in the tray to get a desired look.
Hope this helps.
