Oops, forgot to add that the thickness of the slats should be 1/2 to 5/8" thick.

Any lumber yard, home improvement store, many hardware stores, pallets, ebay, and craigslist are all sources for wood (some free.) Cut to width, thickness and length and you've got as many replacement slats as you need. If you are incapable of doing this type of work, hire a good carpenter.

Good luck with your project ;-)

Thanks for your suggestions and advice Rock and Bobs.

Hubby says he's got some 6-foot lengths of Curly Maple in the exotic wood pile in our garage from his old turning bowls and other lathe project days (He's made some really nice stuff on the lathe, but how many more bowls do I need? LOL). Since we have the wood, and it's not being used, is that wood suitable? Might you have a better suggestion for wood type?

I think he has enough equipment to plane to thickness, etc. Finish carpenter, hubby is not. But he says "it's not rocket science!" This, from a guy who thinks crooked nails are for around corners?????

Curly maple is notoriously difficult to machine with a surface planer. The surface quality might be very poor, and it would be a waste of expensive wood. I'd lean towards walnut, hickory or oak.

Are you going to have this outside, exposed to the elements? If not, paint-grade poplar is both easy to work and great to paint, and economical.

Yes, Bobs, the chairs are exposed to the elements, sitting on porcelain tile patio floor in brilliant, day-long, full CA sun with occasional spray from sprinklers (depending on the wind). Chair frames are of very heavy aluminum (powder coated grey/beige) so water is not a problem with the metal part.

These chairs had/have heavy duty vinyl strapping on the seats and backs. Only the vinyl on the two chair seats got discolered over the years, backs are still perfect. The plan: replace seats with wood slats, drill holes in the non-circular tubing seat frame sides, screw the slats down half way through the elongated (hollow) metal tubing.

Why go through all this trouble, you ask? We have four additional matching chairs that sit in the shade around a table that are still in perfect shape and sometimes want to seat six around the table.

In that case, might I suggest unfinished ipe'? The city where I live kept having park benches rot out and finally at the suggestion of the lumber store replaced them with ipe' and it looks great.

Here is a link that might be useful: Ipe information

Thanks again Rock, Bobs and Jon. Will start the hunt for wood of the types you have suggested for making the chair seat slats. Hopefully I can talk hubby into saving his exotic woods for something really special, or sell the whole variety that's stacked in the garage.

Our son gave me a small piece of Ironwood scrap from one of his projects (first I'd heard of Ipe) that's now hanging as the clanker on a windchime. Unbelievable! That stuff DOES NOT float!

Do you make or know who has curved pieces for back support for cast iron benches?