There is much conflicting advice about how to care and clean decanters - expecially antique ones. Here are a few 'dos and don'ts'
1) After use, wash your decanter as soon as practicable in warm water - no hotter than you hand can take when immersed in it. Add a VERY small amount of detergent if necessary. Then rinse twice with clean water and invert it to drain. Be very careful when draining over a sink that the decanter cannot slip and break.
2) If a decanter has become stained by leaving red wine, sherry or port in it, break 2 or 3 denture cleaning tablets into the decanter and half-fill it with warm water. Leave for about an hour, then rinse and drain (see above). Repeat if necessary.
3) If a decanter has a cloudy whitish film on the inside, there is NOTHING you can do about it - do not try to swirl lead shot or glass balls in the decanter as they can make the problem unsolvable. There are a very few professionals who can polish the inside of decanters. It may cost £25 - £40 - but it can be worth it. Ask us if this is the case.
4) Decanters must be kept dry when not in use. To dry a decanter, first take a small sheet of newspaper and roll it into a long thin sausage before putting it in a low oven for 15-20 minutes. Then insert the paper into the decanter and wait for the moisture to be absorbed. It may need repeating several times. Re-useable decanter dryers are available commercially and are tubes of gauze filled with deliquescent cristals.