[PhilG007]

As the header says,when is 4NT not Blackwood?. I'm launching the post for the purpose of
edifying any novices/beginners/intermediates who might be viewing this topic. I know from experience
this age old question can be a confusing issue with the result that slams are being missed when they shouldn't be and slams being bid
when they shouldn't be.

[Stephen Tu]

For my partnerships, it's whenever it could conceivably be quantitative, usually over partner's natural 1nt/2nt/3nt bid, and/or no suit has been agreed, or a minor has been agreed (different methods over minors). It is blackwood if you go out of your way to show a strong single suit first then follow with 4nt even if partner bid 3nt. And if there is an easy way to agree suit in forcing manner before 4nt, always use it to avoid ambiguity, since we are typically using RKC blackwood and suit ambiguity can be rather deadly.

So, not blackwood:
1nt-4nt
2nt-4nt
2c-2d-2nt-4nt, or similar sequence after Kokish relay
1nt-2c-2x-4nt
1nt-jacoby xfer-accept-4nt
2nt-3c-3x-4nt
2nt-jacoby xfer-accept-4nt
similar sequences after 2c-... 2nt showing a 22+ or 25+ NT.
natural sequence ending in 1nt/2nt/3nt offering to play in NT, followed by 4nt
No suit agreement, above 2nt, it's possible you have a hand that is too strong for just 3nt. E.g. 1s-2h-3d-4nt. (set a suit to bid blackwood later)
Partner pulls your natural to play 3nt to 4m as a natural slam try, and you revert to 4nt, e.g.
2nt-3s!-3nt-4d(nat diamond try)-4nt
xfer then new suit after 2nt, opener has no fit
2nt-3h!-3s-4c(nat spades/clubs, forcing)-4nt

blackwood:
1nt-texas-accept-4nt
2nt-texas-accept-4nt
if major suit has been agreed.
if minor suit agreed and we are not playing either minorwood or kickback
shown GF single suiter with 3M (e.g. after a strong jump shift), and partner bid 3nt.

Main thing beginners need to focus on is 4nt is not blackwood if partner opens in NT, either immediately, or as the 2nd bid after stayman/jacoby. If you use stayman, you have to teach them methods to agree the major in a forcing manner, which usually involves bidding something like 3 of the other major (which has no use if Jacoby xfers are used to show just holding the other major), or perhaps the Baze convention.

[NickRW]

PhilG007, on 2017-October-17, 16:20, said:

As the header says,when is 4NT not Blackwood?. I'm launching the post for the purpose of
edifying any novices/beginners/intermediates who might be viewing this topic...

Although I know I'm "peeing in the wind", beginners, at least, would be better advised to learn how to cue first and leave 4NT as natural. The numbers of players (many having years and decades of experience) who do not know when Blackwood is inappropriate and do not know what to do about it is one of the worst things in bridge.

[The_Badger]

Blackwood 4NT: the most abused convention in the history of bridge

[Tramticket]

Stephen's list is pretty comprehensive, but some of it is system dependent, so for example we don't usually play Texas transfers in Acol. The rule could be modified to:
1NT-Jacoby Transfer-accept-4NT = Quantitative
1NT-3M (Natural slam invite)-Any-4NT = Blackwood

Also the default position over here seems to be that a sequence such as 1♠-2♥-3♦-4NT is Blackwood, setting the last suit as trumps. Some would play that it is Blackwood, setting the first suit as trumps. I'm not saying that either of these is optimal (I prefer Stephen's methods), but if you and partner are agreed you will have a playable method.

[Tramticket]

The_Badger, on 2017-October-18, 04:05, said:

Blackwood 4NT: the most abused convention in the history of bridge

Agreed. But if taught properly and used properly it is one of the most valuable.

[aguahombre]

Simpler to make your rule "When is 4nt asking for key cards?"

Recommended:

If playing Kickback, 4nt is KC only if Spades are ESTABLISHED as trump.
If not, 4nt is KC only if a Major is ESTABLISHED as trump.

Then your partnership confirms what 'established' means. For instance, JTB does not establish; Texas does establish.

[PhilG007]

The_Badger, on 2017-October-18, 04:05, said:

Blackwood 4NT: the most abused convention in the history of bridge

Exactically Which is why I raised the topic in the first place

[PhilG007]

aguahombre, on 2017-October-18, 05:40, said:

Simpler to make your rule "When is 4nt asking for key cards?"

Recommended:

If playing Kickback, 4nt is KC only if Spades are ESTABLISHED as trump.
If not, 4nt is KC only if a Major is ESTABLISHED as trump.

Then your partnership confirms what 'established' means. For instance, JTB does not establish; Texas does establish.

Not everyone plays keycard blackwood despite it being an excellent update on the original convention.

[barmar]

PhilG007, on 2017-October-18, 07:57, said:

Not everyone plays keycard blackwood despite it being an excellent update on the original convention.

Well, they should. It's generally tops lists of most useful conventions. You get important extra information (trump king and queen, and ability to find out which side kings partner has) and give up practically nothing. Are there any good players who don't play some form of keycard ask (I'm including variations like Kickback and Minorwood)?

I think experts have one exception, though: 1Maj-4NT is regular Blackwood, not RKCB -- responder must start with a game-forcing raise if they want to ask for keycards. But it's not that important (I don't think I've discussed it with most of my partners) and novices can just ignore this wrinkle.

[Cyberyeti]

I agree with basically all of the long list above.

Sequences like 1♥-1♠-2♦-3♣-4N are "I want to bid NT but am too good for 3N" type as are 1x-1y-2N-4N.

One thing I'd recommend to discuss is how you handle 1N-2m-2♥- 4N should be quantitative, but you might want to discuss a forcing way of agreeing the major suit or ask aces. We use 1N-2♣-2♥-3♠ as GF slam interested agreeing hearts rather than a splinter and 1N-2♦-2♥-4♠ as asking aces (and I'd recommend doing that one even if you don't play KB anywhere else)

[barmar]

Cyberyeti, on 2017-October-18, 09:26, said:

One thing I'd recommend to discuss is how you handle 1N-2m-2♥- 4N should be quantitative, but you might want to discuss a forcing way of agreeing the major suit or ask aces. We use 1N-2♣-2♥-3♠ as GF slam interested agreeing hearts rather than a splinter and 1N-2♦-2♥-4♠ as asking aces (and I'd recommend doing that one even if you don't play KB anywhere else)

While I use some similar gadgets with regular partners, I think that's getting a bit complicated for the novice players for whom this thread is targeted.

I'm not sure how the last sequence would come up if you play Texas, which I think I would teach before that.

[Cyberyeti]

barmar, on 2017-October-18, 09:34, said:

While I use some similar gadgets with regular partners, I think that's getting a bit complicated for the novice players for whom this thread is targeted.

I'm not sure how the last sequence would come up if you play Texas, which I think I would teach before that.

Sorry, almost nobody in the UK plays Texas. (we use 4♣ gerber, 4♦ 5-5 majors either to play or definitely ongoing with the invite going thru the transfer)

I've heard after 1N-2♣-2♥-4N-P "Well if I can't ask aces, what do I do ?" so many times, I was merely suggesting people discussed it.

[Zelandakh]

Cyberyeti, on 2017-October-18, 10:06, said:

Sorry, almost nobody in the UK plays Texas.

Really? I think I have played it with every one of my UK partners, mostly in combination with 4♣ majors and no Gerber, and it was practically de rigeur amongst the peer group in Aberdeen. I am not sure that Norfolk is a good proxy for the whole UK here....

For your specific auction, 1NT - 2♣; 2M - 4NT, one of my favourite tricks is to extend the old SID convention to cover GF raises, thus covering the RKCB hands in the same way that 2NT does for most over a 1M opening.

[Cyberyeti]

Zelandakh, on 2017-October-18, 11:41, said:

Really? I think I have played it with every one of my UK partners, mostly in combination with 4♣ majors and no Gerber, and it was practically de rigeur amongst the peer group in Aberdeen. I am not sure that Norfolk is a good proxy for the whole UK here....

For your specific auction, 1NT - 2♣; 2M - 4NT, one of my favourite tricks is to extend the old SID convention to cover GF raises, thus covering the RKCB hands in the same way that 2NT does for most over a 1M opening.

Nobody played it in Cambridge either when I was there, but that was a while ago, I suspect more American ideas are making their way in. And Norfolk is not as far in the dark ages as you might think, we had one pair that played Fantunes (without the undocumented bits), our county captain plays polish club and we have a growing band of Swedish clubbers.

[Tramticket]

Cyberyeti, on 2017-October-18, 10:06, said:

I've heard after 1N-2♣-2♥-4N-P "Well if I can't ask aces, what do I do ?" so many times, I was merely suggesting people discussed it.

As I suggested up-thread, in a weak NT context, the sequence 1NT-3M should be natural and game forcing. It sets the suit at a lower level than Texas transfers and there is no need to worry about "Wrong-siding" when responder holds the stronger hand. Either partner can cue-bid or use Blackwood.

And I agree that few in the UK, who play a weak NT, use Texas transfers.

[Zelandakh]

Tramticket, on 2017-October-18, 12:38, said:

As I suggested up-thread, in a weak NT context, the sequence 1NT-3M should be natural and game forcing. It sets the suit at a lower level than Texas transfers and there is no need to worry about "Wrong-siding" when responder holds the stronger hand. Either partner can cue-bid or use Blackwood.

And I agree that few in the UK, who play a weak NT, use Texas transfers.

All of the regular partnerships I have been in played a weak NT too - Texas works with it just fine.

As for 1NT - 3M, while I agree with you that it is a good idea to be able to set the suit at the 3 level and initiate cues, I also believe that there is a better way of achieving this aim than the direct 3 level bids, meaning that they can instead be put to another use (such as handling awkward 3-suiters). What matters in the end is that the whole structure fits together harmoniously - that is as true over a weak NT as a strong one.

[barmar]

Tramticket, on 2017-October-18, 12:38, said:

As I suggested up-thread, in a weak NT context, the sequence 1NT-3M should be natural and game forcing. It sets the suit at a lower level than Texas transfers and there is no need to worry about "Wrong-siding" when responder holds the stronger hand. Either partner can cue-bid or use Blackwood.

And I agree that few in the UK, who play a weak NT, use Texas transfers.

True, if you play weak NT, Texas is not as important. With strong NT, you might use Texas with a 7-8 count and a 7-card suit, so you still want the lead coming up to opener.