The classic soak bath is a mix of isopropyl alcohol with a generous amount of concentrated aqueous KOH. The disadvantage is that is tends to evaporate over time, is flammable and it shouldn’t be poured in the sink because EPA can bust you for sending isopropanol down the drain. There is one good base bath alternative without isopropanol – that contains aqueous KOH with K3PO4 (or any other K-phosphate, with extra KOH to make stuff strongly basic) mixed with some diluted anionic household floor-cleaning detergent. A common grade based on greasy-chain sulfonic acids works best. The foaming is not much of a problem if you don’t overdo it with the detergent, few spoons is enough for a bucket. Please note that Na-phosphates or NaOH cannot be used as a substitute because Na3PO4 hydrate is poorly soluble and crashes out of the mix. Also some weird detergents tend to form an oily layer if the mix is too concentrated and salty – on the first try one should test the compatibility of the detergent before mixing vats of the bath solution.
This phosphate-based alkaline bath without iPrOH works very nicely for an overnight soak and I would encourage all alkaline bath-lovers to give it a try.
I wash my dirty glassware as soon as it is produced – it is much easier to wash before the stuff dries on. I prefer doing fewer experiments in parallel but clean and wash inbetween so that at the end of the day the hood is nice and organized again and cleared of the clutter. Hot water and acetone mostly does it for me, for difficult cases the bottles with 2M NaOH, 6M HCl and DMF are at hand. (The particularly nasty pieces of glassware are saved until I feel brave enough to play with piranha mix.) I stopped using base baths because they take space and I don’t like to fish in a bucket full of slippery glassware soaking in a caustic mix. Aluminum parts and frited funnels are eaten in base baths and the forgotten pieces of the glassware are slowly etched. But if you want your flasks picture-pretty then base bath is the way to go.
Update: The actual ratio for a large base bath tank that holds approx 100 liters of of solution is: 1 kilo of common grade 85% KOH pellets dissolved in about 2 liters of water, add 250g of K3PO4 in about 2 liters of water, dilute up to 100 liters total volume, then add a whole bottle of liquid non-scented color-free laundry detergent containing 32 laundry loads (we use a Publix grocery store “Free and Clear” brand with a little dirty boy on the bottle, it is supposed to contain a mix of anionic and non-ionogenic detergents and costs about $3 a bottle)