Stickiness is connected to your conditioning product. You can scour all the stickiness off your bridle, but then what do you use to condition it?
The lower-priced wipes and spray on conditioners all leave a sticky mess on everything, IME.
Here’s my similar conundrum:
I have a similar issue with an older Stubben bridle that I bought second-hand. Basically, the shine is off the leather, so the leather is rather matte.The bridle is black, so dust and dirt show up immediately.
I cleaned last week and scrubbed with glycerine saddle soap and a terry cloth, dunked the whole thing in a bucket of hot water. That absolutely got all the dirt and stickiness off, but left the leather feeling dry.
So then I had to slather on a generous amount of Passier Lederbalm on both the rough and smooth side of the leather. I like how it conditions leather, but on this particular bridle it does seem to leave it sticky. And it was picking up visible dust as soon as I put it on the horse!
I like how the Passier product cares for leather in general and haven’t had this problem on other gear. But I think for this bridle, I will need to experiment with different conditioners.
When I’ve had to resurrect genuinely old tack, like the pile of dried-out straps from 40 years ago that is now a perfectly fine double bridle, I have washed and soaked them, then tossed them into a tub of mineral oil for a week, or in the case of the double bridle, six months. This has actually worked really well, once the excess oil has dripped off a bit. But I can’t bring myself to do this to anything that is still more or less “good,” i.e., recognizable as a bridle :). It’s more a last-ditch “can this bridle be saved?” move.
I did get a sniff of someone else’s Effax Ledersbalm, and it looked like it might be less greasy and sticky than Passier, so I might ask to borrow a dollop to try on the Stubben bridle.