more photos:

It’s called window glazing. It is a putty like material that holds the glass pane in place. It gets old and dry and falls out. You can remove the loose stuff and put new in with a putty knife. You can get window glazing at almost any hardware store or big box store.

wonderful! thats what i suspected. thank you!

Clean up the windows really good first. Do not put that glazing on top of mildew.

should i rebuild wood with wood epoxy and then glaze?

more pics

more pics showing the powdery layers falling off with glazing

the house was built in 1906. i know lead paint is an issue but i didnt know about asbestos. how likely is it that this window glazing did indeed contain asbestos? now im worried!

I would not be overly concerned even if I knew the glazing compound contained asbestos.

For one thing, it is outside. Not inside.

For another, it is mostly intact and will mostly come out in chunks. As long as you keep the work outdoors & use sensible precautions, I don't see any reason to worry excessively.

Use chemical strippers to remove the paint--don't sand it off and release a storm of lead dust.

The one certain thing is that these windows are in critical condition. They urgently need attending to if you intend to rescue them.

Is it possible the glazing is really wood (molding)?

thank you @ci_lantro ! I was worried that it wasn't safe to continue working on them! the windows are almost fully stripped. i used a citrus paint & varnish remover gel. i wore a mask, gloves, and eye protection and cleaned up debris. thank you SO much. @Stax i considered if the glazing is real wood but it is very heavy and brittle and does not have any graining.
this window leaked water during ida so i went to weather proof it and saw that it needed a lot of attention. my husband believed it was in good condition but i assured him it needed repairing. we are in a historic new orleans house and i restored the house several years ago (im debating whether or not it was worth the major investment) and i'm finding many shortcuts the contractor took previously and am trying to fix them. i have 13 more of these windows and 2 sets of matching french doors that need repairing as well. thank all of you for your help! i will continue the repairs knowing that i can do so safely. :-)

More than likely it is asbestos, I would avoid dry scraping it, and use lead safe work practices and even more so if you have kids. I would pull the window to work on it since it would make it easier and allow it dry out. It will also be easier to work on . The window looks wet and should be dry before you make repairs . That upper sash is gonna take a lot of time , especially if you are going to strip it and remove all the old glazing. I‘ve done my share of these and it slow and painstaking and a learning curve involved .

@toddinmn yes it’s very wet. That’s what made me inspect it. It leaked water during hurricane ida and took quite a beating. I felt like it had layers of paint caked onto it and water had seeped under the thick layers of paint. I should mention that the first pictures I posted were after removing the majority of the paint. I was shocked to find pencil thin panes! When painted, each wooden section was at least 1” wide. I will remove the window and let it dry out and make the repairs. I’ve repaired other old double hung windows in the past, but have never encountered one with such a large area of glazing. You have been very helpful and encouraging. Thank you!

Please call Steve at Wood Window Makeover.