The primary function of Brooks Proofide is to nourish the leather to keep it supple and to prevent it from drying out with age. With this in mind, it is generally not necessary to apply Proofide to a new saddle. Instead, it is recommended to apply it after every 6 months.
Proofide should be applied sparingly to the upper surface of the leather using just enough to cover the entire upper surface area. This should then be left on the leather for several hours (perhaps overnight) in order to allow penetration through into the inner fibres, before buffing off thoroughly with a soft cloth.
Some Brooks saddle owners use Proofide for two further purposes:
a/ If the saddle is giving excessive discomfort after some time of use, then Proofide will soften the leather and hence encourage it to break-in more readily
b/ If riding regularly over wet surfaces (especially if you bicycle does not have mudguards), then a coating of Proofide applied and left onto the underside of the leather will offer some moisture shielding to the leather
HOWEVER, in both of these two cases, it is very important to be mindful of the irreversible damage that can result from excessive application of Proofide. There is a risk that the leather will over soften and then no longer be able to support the rider’s weight.
Proofide is a tried and trusted product, the ingredients of which are all known to Brooks. This is the only dressing, therefore, that we can endorse for use on a Brooks leather product. The use of any other product is frowned upon and will also jeopardize your warranty rights.

HOW CAN I STOP THE COLOUR DYE FROM STAINING MY TROUSERS?
Brooks uses only natural vegetable-based dyes to achieve the colours of their leather products. These dyes will sometimes ‘bleed’ out during riding usage. This bleeding is more likely to occur when the saddle is new but, over a short period of time, the amount of bleeding will gradually reduce and should soon stop all together. Brooks advise the wearing of dark trousers, or shorts, during these initial rides. If the leather becomes wet, then bleeding may re-commence for a short while, this can also be true after Proofide has been applied.

As I seem to have been drawn into this thread (by proxy, if you will), I feel that it's appropriate that I should try to correct one or two misapprehensions regarding my views on the matter under discussion, albeit somewhat late in the day. E-mail correspondence is, IMO, an unsatisfactory medium in which to express oneself in a lucid and precise manner, and one which tends to exacerbate the old trans-Atlantic 'two nations, divided ....' syndrome, but, as it seems that this stuff is archived (?verb) for posterity, I'll try to make myself plain(er). I don't think that soaking a saddle for longer than 24 hours will really enhance the process - overnight should be more than adequate. Longer soaking may initially improve the appearance of a 'badly cracked' saddle, but no amount of soaking will do anything to 'heal' these defects - if defects they are; most of us, especially if we're of a 'certain age' (only slightly older than most of the saddles that we're considering, in the main?), will have acquired a few cracks and creases of our own, but, although we're told that our living tissue can be 'repaired' to some extent that is not possible with dead animal skin, most (I hope) will prefer to see these 'defects' as conferring a degree of distinction. But, I digress...
The best 'treatment' for a badly cracked leather saddle, provided that it is stll structurally sound, is to ride it regularly, with love and the occasional light dressing of 'Proofide'. Most of these things have languished, unloved and neglected, for many years, and it can be surprising (sometimes, but not always) just how well they'll respond to a bit of TLC.
I think Jerry has mis-understood my comments about the leather 'tearing at the rivet holes' (which is where it usually occurs, of course). 'Abuse and overtightening' implies to me an active assault on the saddle, but I think that most of these things have been damaged simply by neglect; a leather saddle which has been kept in an unsuitable environment, often unused for many years, may well have 'lost it's nature', and the fibers (?American sp.) become brittle - once this has happened, nothing can feasibly be done to 'revive' it. Little mention has been made of my concomitant advice that, after soaking and assessing that it's probable that the saddle still has a life worth saving, it's nearly always important to cleanse the leather with saddle soap; I do this in mildly warm water and, having rinsed the resulting crud away, I rub more soap into the leather and leave it to dry - saddle soap these days seems to contain considerably more glycerine than domestic soaps, and this will probably provide all the 'essential oil' that the saddle needs. As regards drying, I certainly don't advise the use of excessive heat, but I'd think that 'in a dark room' is probably taking it too far the other way; ideally, you'll need a good flow of air in a warm-ish environment - say, by an open window, on a Summer's day and out of direct sunlight, and it should be ready to dress (lightly, and topside only, I'd suggest) with 'Proofide' within 24 hours. However, 'in a dark room' may well be a very suitable environment for maintaining any such saddle when it's not in use; what I'd suggest is ideal, is a slightly damp cellar, with good air-flow and constant mild temperature - certainly no central heating. Might not suit the rest of the bike, though. One thing that Jerry has most certainly mis-understood, is my opinion regarding the quality of the leather that Brooks are using for their current production.
It's quite true that concerns have been expressed regarding the raw material available to tanners these days, and it may well be that even the best finished product 'lacks substance' compared with that available in the past (as has been suggested to me recently, regarding the stuff that I'm using), but I'm quite convinced that the leather used by Brooks (especially that awful material that those poor devils in B'ham are having to use to make the so-called 'aged' models) is nothing like the best that is currently available. I have had conversations with the Italian management of the Company, but I don't think it appropriate that I should discuss these in this forum - even if I had the time, which I really don't have at present.
Tony Colegrave, Northiam, E.Sussex, U.K.