Hi,
Industrial materials such as the steel factory windows started to make their way into homes in the teens and twenties, so yours is a very early example.
They were originally glazed with linseed oil putty, which even in steel sash does dry up and fall out. For a complete redo you'd need to remove the putty, steel clips that actually hold in the glass, and then do whatever sanding and priming that the steel needed, then you'd reglaze with new clips and putty. The putty line on these sash is enormous, I recall that the putty is a 5/8x5/8 triangle, so the amount of putty will be like four times what a wood sash would require. The choice is yours whether to use glazing putty or painters putty (made with linseed oil).
Consider having interior wood storm windows fitted. The house I grew up in (built in 1936-8) had two sets of these windows, and they were very inefficient. The large pair (each 6' x 8') were covered with condensation and ice most of the long upstate NY winter.
Casey

Thanks Casey. These are the only windows in my house without double pane but they are unique and unusual. There are 3 fixed ones and one with a projecting style opening, like they had in industrial new york buildings. They have paint also on the outside that I would like to strip somehow and put some protection on them. Have you ever stripped paint from the metal windows?
Marcia

Old paint will stick to metal for a long time. It would be inconvenient to chemically strip it, and heat is ineffective because the metal conducts the heat away. Your best bet would be to sandblast. But realistically, just scrape and sand. Use a red oxide primer, or a rust converter. If the former, reprime with regular oil-based exterior primer before top coating. If the latter, follow their instructions, different brands of rust converters have different priming requiremets, but most ask for a latex primer. Oh, yea, glaze after priming, then top coat once the glazing skins over, and of course "bed" the glass in a layer of putty.
Casey

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