Hi Rich,
That's a lot of soaking! Is the fur still hanging on or has it started to slip (pull away from the skin)? I've found if you over wet the pelts during the tanning process the epidermis can enter the early stages of decomposition and the fur might start falling out. If it's still holding firm you might want to try the following...
Assuming you've carefully scraped any flesh and membrane from the flesh side of the pelt, lay it fur side down and rub in a softening agent. I always use an egg whisked up in a small amount of warm water or pure soap flakes mixed with olive oil rubbed into the skin side to help soften the fibres. The pelt is kept on a cool place over night to absorb the liquid (it's important not to over wet the pelt at this stage - the fur should still be dry at this point). Next I pat the skin side dry with an old tea towel and pull, poke, prod and stretch it in your hands until the skin side has dried completely. it should change from a dull greyish colour to a bright white shade as the fibres dry and if all those fibres have been worked constantly, they should dry soft and flexible rather than cardboard like. Set aside an hour in a warm environment for this and don't go too crazy as rabbit pelts are pretty thin and easily torn. If you try to 'force dry' it by sitting right near the fire or out in the sun, the pelt will dry too quick and you won't be able to work fast enough to produce a soft, flexible pelt.
Once you're sure the pelt is completely dry you should smoke it. Wood smoke is an excellent preservative, completely free and will preserve your pelt nicely. The longer you smoke it, the more protected it will be from future soakings (a well smoked pelt will stay soft if it gets damp then dries out again but a non smoked pelt will dry stiff unless it's worked soft everytime it gets wet). No wet dog smell either, just lovely wood smoke! Use hard wood chippings over hot coals to engulf any pelts you have in plumes of thick, formaldehyde rich smoke for around an hour minimum or hang your pelts up, spread eagled on a line in the eaves of a group shelter to absorb all the campfire smoke that passes through. Just try not to breathe the stuff in too much.
Not sure if your pelts are intended to become mittens on their own but if I were you, I would use them to make inners only and get hold of a deer hide from any stalker or game dealer to make the tougher outers. Deer hide will go through exactly the same tanning process but on a larger scale, requiring more elbow grease (smaller hides such as muntjac can be hand stretched exactly the same as the rabbit pelts) and more eggs (around 12 for a large fallow so adjust for small roe or muntjac). If hand stretching you'll probably want to remove the hair and make buckskin. Deer hair is pretty good at breaking and falling out all over the place anyway, especially on heavy use garments such as mittens. Also, buckskin will dry a lot quicker than 'hair on' hide. Perfect for mitten outers. If that's the case then right after scraping the flesh off the hide, soak the whole thing in a thick, gloopy solution of hard wood ash and water for a minimum of three days to force the epidermis to slip and you should be able to scrape away hair and epidermis, or 'grain' (top layer of skin, with a grainy pattern like our own skin or the pattern found on shiny leather outer surface) using a blunt draw knife. Incidentally, do all your scraping by draping the hide/pelt over a smooth round log and keeping it taut throughout to avoid puckering which can lead to small nicks and tears. These will only enlarge as you hand stretch the hide later). Once the hair and grain have been scraped off, leave the hide to soak in a running water source overnight (the larger and faster flowing the better to avoid dirtying it and potentially affecting wild life, also well away and down stream from your drinking water collection point). Give what was the flesh side another scrape to remove any last bits of membrane and expel some of the water content to leave it only damp to the touch. Now you should be ready to rub in the softening agent as already mentioned, only difference when making buckskin is that you can soak the whole hide in the mixture to absorb it better. Patting it dry with a tea towel won't really work with larger hides so you'll need to wrap it loosley round a smooth wooden pole and use another stout pole to twist the pelt up tightly and squeeze as much of the mixture out as possible (this also helps squeeze the solution through the fibres a bit more). Keep re-arranging the hide and re-twisting to get it as much of the moisture out as you can. This will make hand stretching much easier and potentially more successful. As already mentioned, hand stretching, softening and smoking are all the same as the above rabbit pelt process from this point and by the end of it you should have something that resembles very soft, smoky suede.
So, got a bit carried away there with a pocket guide to tanning. Hope the information is helpful - let me know how you get on.
Cheers
Joe
www.wilderness-survival.co.uk