Blackwood is a convention.
Blackwood is a slam-seeking convention for asking aces. It is used to avoid bidding slam contracts when two aces are missing for a small slam or an ace is missing for grand slam. Typically it is invoked with a bid of 4NT when a suit fit has already been identified. More generally, any jump bid of 4NT is Blackwood unless it follows directly a natural notrump bid by partner. There are, of course, exceptions.
Blackwood is one of the two most-widely used conventions in the world and is taught to beginners at the very beginning (the other one is Stayman), though many players misuse it. The purpose of Blackwood is to avoid bad slams (i.e. slams missing two aces), but not seeking possible slams holding insufficient strength. Therefore, it is wrong to use Blackwood with a void (voidwood may be used instead).
Standard Blackwood[]
When Blackwood is on, a 4NT bid invokes it:
- 5♣ = 0 or 4 aces
- 5♦ = 1 ace
- 5♥ = 2 aces
- 5♠ = 3 aces
Note that the response to the asking 4NT may be beyond the point of no return for a small slam. Conventions designed to deal with this are Gerber and Kickback.
King asking[]
If all the aces are located, the original 4NT bidder may ask for kings with 5NT. The responses are then
- 6♣ = 0 or 4 kings
- 6♦ = 1 king
- 6♥ = 2 kings
- 6♠ = 3 kings
Note that the 5NT bid guarantees all aces are in the partnership, therefore, the responder may directly bid a grand slam if he certain that it is going to make with all aces.
Examples[]
- 1♥-4NT is Blackwood.
- 4NT opening may be Blackwood.
- 1NT-4NT is a quantitative slam invite and is not Blackwood.
Variations[]
Variations on the responses[]
Responses with a useful void[]
In addition to the standard responses above, the following non-standard responses show a side void:
- 5NT: even number of aces with a void (in case of 0 aces and the opener has not shown a strong hand yet, it is possible to just return to the agreed trump suit without showing the void);
- 6 of a suit below the agreed trump suit: odd number of aces with the named void;
- 6 of the agreed trump suit: odd number of aces with a void above the trump suit.
Key card Blackwood[]
When using key card Blackwood, there are five key cards instead of four aces in total: four aces and the trump king. After the 4NT asking bid:
- 5♣ shows 0 or 4 key cards;
- 5♦ shows 1 or 5;
- 5♥ shows 2;
- 5♠ shows 3.
It is now mostly deprecated and replaced by the method below.
Roman key card Blackwood[]
Roman key card Blackwood (RKCB) is similar to above, with 5 key cards, but with the following responses. After the 4NT asking bid,
- 5♣ shows 0 or 3 key cards (1 or 4 in the 1430 version);
- 5♦ shows 1 or 4 key cards (0 or 3 in the 1430 version);
- 5♥ shows 2 or 5 key cards, without the trump queen;
- 5♠ shows 2 or 5 key cards, with the trump queen.
In general, 5NT is used for king asking. In this case, the trump king is not counted, so there are only 3 kings available in the response. However, the non-trump bid after the response may have different uses, either for asking the trump queen, or to sign off at 5NT.
Some reverse the 5♣ and 5♦ response. This further variant is called 1430 while the normal version is called 0314 or 3014. The advantage of using 1430 is that, there is more likelihood for investigate slam further is 1 keycard is held rather than 0, if the stronger hand is asking for the weaker hand, therefore swapping the responses save a space for queen ask.
- queen ask
The immediate next step after the response, provided it is below 5 of the agreed trump suit, asks for the trump Q. For example, if ♥ is the trump suit, after 1♥ - 3♥ - 4NT - 5♣, 5♦ asks for the trump queen.
The responses are: 5 of the agreed trump suit: no trump queen. 5NT: trump queen without any side kings. another suit: trump queen with the specified king.
- king ask
The standard meaning for 5NT after the response is to ask for a the number of kings, where 6♣ is 0, 6♦ is 1, 6♥ is 2, and 6♠ is 3.
Another possible agreement is to bid 5NT in order to ask for the cheapest king, where 6 of the trump suit if it is not possible to bid one below it.
When Gerber 4♣ is used as the asking bid after NT, there is no such thing called the trump queen, therefore, the higher two responses have some other meaning:
Details on which 2 aces are shown by 4♠ or 4NT responses need further partnership agreement to define. For example, 4♠ may mean 2 aces, minimum and 4NT may mean 2 aces, maximum.
Six-ace Roman key card Blackwood[]
Six-ace Roman key card Blackwood, abbreviated six-ace Blackwood, six-key-card Blackwood or 6A-RKCB, is used when there are two potential trump suits. It is similar to RKCB above, but with 6 key cards (4 aces, 2 kings) and 2 queens:
- 5♣ shows 0 or 3 key cards (1 or 4 in the 1430 version);
- 5♦ shows 1 or 4 key cards (0 or 3 in the 1430 version);
- 5♥, 5♠, 5NT shows 2 or 5 key cards with various queens, details by partnership agreement.
Variations on the asking bid[]
As using Blackwood over a minor suit can easily get the auction too high, some other asking bids have been developed to let the partnership sign off at game.
Responses are counted in steps, therefore
- 5♣ in normal Blackwood (or any variation on the response) becomes 1 step above the asking bid;
- 5♦ becomes 2 steps above;
- 5♥ becomes 3 steps above;
- 5♠ becomes 4 steps above.
Baby Blackwood[]
A jump to 3NT over a 1-level opening is Blackwood. The responses are the same as normal Blackwood, but a level lower.
Exclusion Blackwood (or voidwood)[]
When a suit is agreed, a jump to the 4 or 5 level of the agreed suit is the asking bid and shows a void in the bid suit. Therefore, the void ace or the king is not counted in the response, e.g.
Then 5♣ asks for kings. It is possible to combine Roman key card Blackwood with voidwood, in which the responses show keycards except the void ace.
Kickback[]
When a suit is agreed, a step above 4 of the agreed suit is the asking bid, i.e.
- 4♣ is Blackwood for NT (Gerber is in fact a special case of Kickback).
- 4♦ is Blackwood for ♣.
- 4♥ is Blackwood for ♦.
- 4♠ is Blackwood for ♥.
- 4NT is Blackwood for ♠s.
It is possible to combine kickback and voidwood together by switching 4NT with the suit above the agreed trump suit.
The king asking bid is a step above 5 of the agreed suit.
Redwood is the same as kickback, but applies to agreed minor only. Its name comes from the fact that 4♦ (Kickback for ♣s) and 4♥ (Kickback for ♥s) is a red suit bid.
Gerber[]
Gerber is usually used after 1NT or 2NT. 4♣ is the asking bid for Gerber and 5♣ is the king asking bid.
Minorwood[]
A non-competitive 4-level raise after a minor suit fit has been found is the asking bid, e.g.
The king asking bid is usually a step above 5 of the agreed suit, since 5 of the agreed suit is always a sign off. In the above example, 5♦ asks for kings.
Interference[]
There are some methods designed to handle interference after the asking bid:
DOPI[]
DOPI (and ROPI) is a convention (and a mnemonic) for dealing with interference after a Blackwood 4NT or other ace-asking call. It stands for "(Re)Double-zero-pass-one". In the event of a double, or an overcall below the response showing two aces, then this convention is in effect. Thus,
- Double (or redouble) shows zero (or four) aces
- Pass shows one ace
- One step shows two aces
- Two steps shows three aces
If the overcall is at or beyond the bid for two aces, DEPO is used instead.
DEPO[]
DEPO is a convention (and a mnemonic) for dealing with overcalls after a Blackwood 4NT or other ace-asking call. It stands for "Double-even-pass-odd", and is a generalization of DOPI for when the overcall is too high. If the overcall is at or above the response showing two aces, then this convention is in effect. Thus,
- Double shows zero, two, or four aces.
- Pass shows one or three aces.