Standard Blackwood
Mr. Easley Blackwood first developed his ace-asking idea in 1933 and submitted it to The Bridge World magazine for publication. It was declined, and it wasn't until several years later that it was accepted. It turned out to be a wildly popular agreement, and perhaps one of the very first conventions we learn. (The Stayman convention is probably another.)
When players use this convention, a bid of 4NT asks the partner to use step responses to show the number of aces in his hand. In the early days it didn't matter what the final contract was destined to be, but after Gerber was introduced the previous bid could not be 1NT, 2NT, or 3NT. The Blackwood convention is used to ask for aces only when the final contract will be in a suit.
After a bid of 4NT, these are the steps, as devised by Blackwood:
5 | 0 or 4 aces |
5 | 1 ace |
5 | 2 aces |
5 | 3 aces |
Most players agree that asking for kings tends to confirm that the partnerships has all the aces and the responder may simply bid the slam at the seven level if he has an appropriate hand.
The responder should not count a void as an ace! Many of our top players recommend jumping to the 6-level with a void in the bid suit. The jump bid also promises three aces. A response of 5NT shows two aces and an unspecified void.
Today, Roman Keycard has almost completely replaced the standard version, but despite its wide popularity it has some fatal flaws that need to be addressed. Eddie Kantar wrote four books describing those flaws and methods to circumvent them. Still, two players will sit down to play togerther for the first time and one will ask, "0314 or 1430?" When the other replies, "I prefer 1430!" They go on to the next topic in filling out a convention card. So much for Eddie's four books!
Although a void may be as good as an ace, it should not be counted as an ace.
Most players will avoid using Blackwood if they have a void in hand, or two small cards in a side suit. If you hold the hand below and you ask for aces, suppose your partner tells you he has one. Is it the valuable club ace, or is the worthless diamond ace?
(Imagine that... a worthless ace.)
Roy Wilson