Leather strap and Nitro finish

I didn't see this thread when it started but now that it has been brought back up. I will chime in.

I can 100% verify that the tanning process of ten/brown leather straps can negatively affect nitro finishes. I have a PRS that has a nitro finish on it that I had a brown birds strap on. I ran my self short on time one day and just stopped playing and hung it on the wall hanger and walked out of the room. I use strap locks and thank God that I do.

The strap was just touching the back side of the body a little. It hung here for several days before I grabbed it to play again. I noticed a slight rough spot where the strap had been touching the guitar. It isn't real bad so it isn't the end of the world. If I had not had strap locks on the guitar it would have made much more firm contact with the finish and the etching would have been way worse. I have not left a strap on a nitro guitar (any brand) since.

I am not sure that black tanned leather has this same issue. I have always heard of it happening with brown or tan leather. My experience was with brown leather.
It's never too late to ask questions and seek advice. When it comes to nitro finish on guitars, it can be sensitive to certain materials, including leather. While leather straps can potentially cause issues with the finish over time, it largely depends on the specific type of leather and the chemicals used in the nitro finish.
Yeah, that's the annoying thing. Anecdotal evidence makes it difficult to come up with a general rule. The leather on one brand of straps may be perfectly safe on all nitro finishes, but another brand that looks identical will have used some sort of conditioner in the leather that destroys nitro.

Or conversely, there may be a nitro finish that reacts to some materials poorly, but those same materials on another nitro-finished guitar are non-reactive.

So the best course of action is to play it safe - use cotton (100%) cloths to wrap your stands/hangers, or keep it in the case, and either way take the strap off when done playing.
I went through asking PRS, looking at what Hercules and Fender say (they say they are nitro safe, but don’t guarantee it). PRS only commits to their hanging stand (and maybe the wall hangers - I can’t remember) as being safe for their nitro finish. I don’t think PRS actually guarantees nitro safe either. I’ve joined the case it unless you’re playing it camp, put the strap on before you play, take it off when you’re done. My final take? Nitro is a pain in the arse.

Side note - my poly ‘03 Santana came to me with the dimargio or whomever strap system with the permanently screwed on dangly “strapettes”. It seems to work, but I hate the dangly thingies. I’m thinking about trying the Ernie Ball locks.
So another dumb anecdote that I just observed (see the thread bump for the SIlver Sky if curious why):

I was playing my Silver Sky, 2020 model, so therefore has a nitro finish, and put it back up on its cotton-glove-finger covered hanger, when I realized that I never take the strap off. From the nitro covered body. It's a PRS strap (one of those hootenanny styles) with leather ends. There has been no reaction with the body around the strap pins. Phew, but dang...I was so careful with the hangers I forgot all about the strap...
Adding to the anecdotes, I generally keep 2 of my guitars out on Hercules stands. One is a 2018 McCarty with a Poly finish. For the past 3 months the other is a 2022 Tremonti with Nitro (one of my other '22 Tremonti's was on the same stand for the previous 9 months). Both use Schaler strap locks and ~75% of the time have a PRS black leather strap attached. I have not seen any change in the finish at the headstock nor where the strap contacts the body by the strap lock. While a short period, so far so good.
So, Hercules stands or hangers, cotton wrapped. Black PRS strap with strap locks. Healthy dose of paranoia (aggghhhh, there’s a cop in the trunk! Oh Shiite, slow down, toss the stash, TOSS THE STASH!)…

(Sorry, flashbacks to a much different time)
I have used the cheap Earnie Ball straps for decades , Leather Ends , Nylon strap and always leave them on all my guitars when hanging ( not in the cases ) . also swear by string swing hangers.
I have also never had an issue with real leather straps and Nitro guitars ( IE Gibson , Martin ) including the PRS strap I use on my 335.
What I have seen issues with is swede , and plastic based ( Vinyl , ( some ) Nylon etc ) Black foam stands , and bug spray, dry erase markers . I've fixed a few Nitro burns in my day, Both Gibson and Fender in the 70s often shipped with plastic backed straps that did a nice job of doing a relic job.

Room 1 by https://www.flickr.com/photos/152274366@N08/
The daughter of a Forum member makes the covers. They're from cotton sock, I believe. She sows them up so you put on on each side of the hook. Visually, they look a little bit like putter covers. I use the Hercules auto lock hangers, as well. They work well on them.
Glad you are enjoying them Jim!

They are actually made from microfiber towels. I’d worry about plain cotton (like a t-shirt) potentially causing small scratches in the finish.
Just buy guitars with rosewood necks. Then the wall hangar doesn’t really matter. And as far as straps, I put Dunlop strap locks on all my guitars. Makes it super easy to take off and put on the strap. Plus I have 2-3 nice straps and just switch them to whatever I’m playing. I recently tried the loxx strap locks. They do seem nice, but I don’t want to change everything over. And I like how the dunlop ones hold the strap away from the guitar. Plus I can still use a regular strap if I need to for some reason. So I’ll probably stick with them.