Blackwood is for Everyone
Blackwood is one of the two conventions -- Stayman being the other -- that I consider indispensible and that I think should be taught right along with the point-count system from day one. And there are three points I would like to make about this convention, to wit:
1. On balanced hands, Blackwood won't tell you what you need to know. After all, four aces and four kings only add up to 8 tricks and indeed, I did come across a remarkable hand with those 8 top honors where that was the limit of trick-taking potential! Not even game in no trump was available. With balanced hands, rather, you'll want to be guided by the figure 33 in point-count. This is a figure adduced by Charles Goren, Oswald Jacoby among other luminaries, not a number I selected out of thin air. See The Figure Thirty-three. On top of that, you're encouraged to keep your eyes peeled and do a little surveying of your own to see if that figure makes sense. If you find a better one, lemme know.
But without the infrastructure, without the lower honors and a healthy supply of them, Blackwood won't do anything for you. How do you know if you've got 33 hcp's? We'll start with a no trump opening, or two no, to be sure. Now the partner of that no trump opener should have a pretty good grasp of the side's potential (with a balanced hand). He adds his count to what a partner has promised, and this should land him in one of three camps: clearly not up to 33, perhaps 33 on a maximum for his bid, and definitely 33 hcp's (but not up to 37!). The path to take with the first and third possibilities is self-evident. In you wind up in the "maybe" camp, one traditionally leaps to 4 no, which is not Blackwood but "quantitative". Actually, some will treat that as quantitative with a minimum and pass, but with a max, bid their aces as if that were straight Blackwood on the ground that we might as well use that opportunity for checkback just in case we are missing two aces. Of course, if you've counted right, you can't be missing two aces on 33 hcp's, but it doesn't look to me as though that policy would do any harm, and I can think of one hand where it would have saved a lot of partnership acrimony (described below).
But wait a minute, fella! Sure we can't be missing two aces with 33 hcp's, but we could be missing the A and K in a suit, no? Yes, to be sure, you could be missing an A K, but I think you could guess the counter-argument to that, which of course is that this is going to be rare enough -- and in itself doesn't guarantee losing two quick tricks unless both honors lie with the opening leader -- that we accept that unlikely turn of events for the many times we profit by paying attention to 33. Back in the days when 16 to 18 hcp's was the standard No Trump opener, Goren said an opening no trump bid facing a no trump opener should be met with a leap to 6 no. Well, 16 plus 16 just comes to 32, no? But presumably the maestro figured that was unlikely enough -- and by no means portending certain defeat -- that you can live with occasional mishaps.
The link above gives many cases where people didn't pay much attention to this valuable figure. My favorite is the time two Life Masters decided to bid against each other to the point where they were in 7 no missing the A of hearts, which not so incidentally lay with the fellow on opening lead. The opening bidder had a tame 13-hcp hand, while the responder had 19 hcp's. Yes, only 32 hcp's, but what the hey. The opening bidder might have had 14 or 15 hcp's, no? You're not always going to get exactitude. Anyway, the bidding went like this: one club, one diamond, one heart, one spade, one no trump, 4 no trump, 6 no trump, 7 no trump (double, of course). At one no trump, the hand should have been clarified. Yes, the opener could have a minimum 13 hcp's as just mentioned, but you're not going to get perfection in this world, and everything was close enough for a leap to 6 no, which in fact would have made and not so incidentally, would have been clear. (Actually, as 2nd bidder protested, "Why can't you tell me the number of aces you have?" the opening bidder said she took the leap to 4 no as quantitative -- a peculiar position to take, since she had a minimum and on that intepretation should have passed. I dunno.)
In any event, you're going to have a few definite hands and a few not so definite, and I would recommend bidding slam when you may have 33 or 34 hcp's and may not also. But if you know your max is 32 hcp's, I would steer clear. Oh, yes, some of 'em will make, but don't forget that if that's a known max, you may be at 31 or even 30 hcp's. And those are tough hands to try to bring home 12 tricks with.
When there hasn't been a no trump opener, or response (as in one diamond, two no) or rebid (one club, one heart, two no), but the bidding has been strong and vigourous (and the opponents don't horn in with 5 clubs or 5 diamonds), when the four no bid is available, I think it a poor practice to bypass this convention, except . . . if you hold first round control in three suits and second round control in the fourth, you might just say to yourself, "We're going to slam whether my partner's response shows we have 3 aces or 4." Otherwise, I can't say much for those who just jump to 6 hearts or diamonds, missing two aces, which they could have determined at no cost. In other words, Blackwood is really a check-up to see that you're not missing two aces with all your strength. It doesn't tell you you're strong enough for slam, a potential that should be established in the earlier rounds of bidding, but will often warn you that you're missing two aces.
When I was doing a daily hand, I often headed a hand with this rhetorical question: "Blackwood is for Sissies?", playing on Art Linkletter's famous dictim: "Old Age is not for Sissies." Anyway, I was always coming across hands that had been bid to slam missing two aces because one of the partners simply decided Blackwood was sissy stuff, not for sophisticated bridge players like him.
Some years back, maybe in the sixties, a strong Italian group, the dominant players at the time, added a wrinkle to Blackwood, which was to count the K of trump as a fifth ace! A fifth ace! Wait a minute: all the 5-level bids are taken up with showing from zero to 4 aces. How could they handle that? And the answer was that the 5 club and 5 diamond responses were designated as showing one of two different numbers. Fr'instance, 5 clubs might indicate zero or three aces, the difference presumably being evident by how much strength that responder had shown previously. After all, we are talking about a difference of 12 hcp's. And by extension, 5 diamonds would show one ace or four. Some reverse those figures, such that new partners commonly ask, "Do you play 0314 or 1403?" meaning do you play 5 clubs as showing 0 or 3 aces, 5 diamonds 1 or 4, or do you play 5 clubs shows one ace or four, diamonds zero or three?
Would that that were the gravest difficulty in incorporating this wrinkle into Blackwood. Misinterpreation of what constitutes trump suit is one wide cobblestoned avenue causing many a stumble. My favorite is the one where one partner had a rock-solid heart suit down to the 9 and nothing else. After they'd see-sawed back and forth trying to find the best spot, the partner of that player went to 4 no and got a 5 spade response. Five spades! Gee, that's always such an encouraging response to normal Blackwood. But looking at the hand, I couldn't imagine where he got it with nothing outside of the heart suit, nary an honor. And then it dawned on me. I didn't mention above that 5 hearts shows two aces, same as with regular Blackwood, except that it denies the Q of trump, for with two aces and the Q of trump, you bid 5 spades!
You get the picture now? The hand with all the hearts thought it was self-evident that hearts were going to be trump. And by this presumption, he saw himself as holding "two aces", since he had the K, plus the Q of trump -- making 5 spades the correct response. Unfortunately, his partner went to no trump, which didn't fare well, since he didn't have a heart in his hand! And thus had no entry to that solid six-card suit.
Well, there are other war stories about misapprehension of what the bid means. Here I only want to say you'll have to be careful using Roman Key Card. With this new wrinkle, it can and does lead to many a butchered bidding and low board.