Is polyurethane coated cast iron going to rust?

Basically the question in the title as I'm not sure if moisture / water can penetrate through polyurethane.

Maybe someone has some insight or experience with this. Is polyurethane water resistant? Is water able to go through it?

Also another question: Is polyurethane biodegradable and does it corrode?

Thanks.

Water resistant? Absolutely. Water proof? No. If you submerge them, water could probably get in where they contact the bar. It's not something I would worry about unless you leave them uncovered outside in the winter.

[QUOTE=radrd;1638095293]Water resistant? Absolutely. Water proof? No. If you submerge them, water could probably get in where they contact the bar. It's not something I would worry about unless you leave them uncovered outside in the winter.[/QUOTE]

Isn't there polyurethane under the stainless steel insert too? I guess then contact with water isn't possible.

In fact I would like to have plates that are weather resistant as much as possible while still being relatively thin.

[QUOTE=gymno98;1638097493]Isn't there polyurethane under the stainless steel insert too? I guess then contact with water isn't possible.

In fact I would like to have plates that are weather resistant as much as possible while still being relatively thin.[/QUOTE]

Assuming anything is waterproof is a stretch unless the manufacturer guarantees it. I'd just ask them.

[QUOTE=radrd;1638098143]Assuming anything is waterproof is a stretch unless the manufacturer guarantees it. I'd just ask them.[/QUOTE]

I once asked them on the phone and the guy said that the cast iron won't rust but the stainless steel insert could show some rust after a long time.

[QUOTE=gymno98;1638098333]I once asked them on the phone and the guy said that the cast iron won't rust but the stainless steel insert could show some rust after a long time.[/QUOTE]

If so, rust can be taken off with a wire wheel or just a good scrubbing. Or throw on some 3n1 oil here and there and you shouldn't have any issues. It's equipment and it won't remain pristine unless you opt not to use it

The water can't permeate the PU, but the PU isn't necessarily air/water tight. If there are any nicks in the coating or any uncoated areas behind the hub, that's a potential point of intrusion. The stainless hubs always rust and it doesn't take all that long.

[QUOTE=Duplicitous;1638100153]The water can't permeate the PU, but the PU isn't necessarily air/water tight. If there are any nicks in the coating or any uncoated areas behind the hub, that's a potential point of intrusion. The stainless hubs always rust and it doesn't take all that long.[/QUOTE]

That, and any time there is a seam it's never 100% unpermeable if submerged. However unless you live in a flood zone, probably ok.

That said, I would advise against leaving any kind of equipment exposed to the elements. I get the idea of an outdoor gym and think it'd be cool, but be realistic about the longevity and maintenance needs of even the highest quality equipment in those conditions.

[QUOTE=broganoff;1638132763]I get the idea of an outdoor gym and think it'd be cool, but be realistic about the longevity and maintenance needs of even the highest quality equipment in those conditions.[/QUOTE]

I still agree with this and would just get cast iron plates for outdoor use. They'll oxidize but you can clean them occasionally. If they corrode significantly in a few years, just replace them. Don't invest a lot.

[QUOTE=radrd;1638134163]I still agree with this and would just get cast iron plates for outdoor use. They'll oxidize but you can clean them occasionally. If they corrode significantly in a few years, just replace them. Don't invest a lot.[/QUOTE]

I thought about buying cast iron plates but lets do the math: polyurethane plates cost 4€ per kg and cast iron plates (with handles) cost 2,9€ per kg.

The cast iron plates I'm referring to can be seen in the picture I attached (since I can't post links yet).

The difference per kg is 1,1€ which isn't really much money saved to be honest since polyurethane is an expensive material too. I guess it depends how much longer the lifespan is with the polyurethane compared to painted cast iron. The cast iron plates are fine pored (don't know if you can say that in English) which means it should rust somewhat slower.

One thing though, cast iron is loud. It will clang and make noise when putting the weight on and off and while lifting. Polyurethane plates will only make a little noise since there's only one metal to metal contact point being the stainless steel insert and the barbell sleeve. On another note though when putting a collar on the sleeves and the cast iron plates sit tightly against each other noise can be minimized quite a lot.

Price wise cast iron is cheaper, though not really that much. I still don't know what to do unfortunately.

FWIW PU colors will degrade quickly in direct sunlight. Structural damage will eventually occur, but how long it will take depends on the makeup of the PU. I imagine cheap PU plates will degrade faster than quality plates.

[QUOTE=Duplicitous;1638201293]FWIW PU colors will degrade quickly in direct sunlight. Structural damage will eventually occur, but how long it will take depends on the makeup of the PU. I imagine cheap PU plates will degrade faster than quality plates.[/QUOTE]

Regarding price and from an economic view, would you say that simple cast iron plates make more sense?

Is noise a problem with iron plates?

[QUOTE=gymno98;1638204453]Regarding price and from an economic view, would you say that simple cast iron plates make more sense?

Is noise a problem with iron plates?[/QUOTE]

If I had to put plates outside, I would hop on FB Marketplace and get the cheapest plates I could find.

I don't think noise is a big issue if you get some good collars (e.g. Lockjaw or similar), but weightlifting is generally not a silent event. :D

[QUOTE=Duplicitous;1638232083]If I had to put plates outside, I would hop on FB Marketplace and get the cheapest plates I could find.

I don't think noise is a big issue if you get some good collars (e.g. Lockjaw or similar), but weightlifting is generally not a silent event. :D[/QUOTE]

And in general do you see a purpose in rubber or urethane coated plates? Or is simple cast iron the way to go?
I'll probably store the weights in my garage and take them out when I'm training.

[QUOTE=Camarija;1638233793]It sounds like your main concern is corrosion resistance.

The only plate I know of that is actually corrosion resistant (marine grade stainless steel) comes in at ~11.40€ per kg.

The Watson Pro Olympic Weight Plates



^ this is the best advice realistically speaking. Just get whatever plates you want, and scrub off the rust occasionally.[/QUOTE]

I honestly thought about buying the watson plates and the price is just too high to be worth it. Even because of corrosion resistance it doesn't really make sense.

Watson plates actually cost ~16€ per kg including shipping and tax so it's a lot. I can buy cast iron plates for 2,9€ per kg and replace them 5 times and I still wouldn't be at the total price of the stainless steel plates.

If I buy the cast iron in Poland I even come in at ~1.8€ per kg so I could replace that 8 times. So in summary not worth it even if the cast iron rusts away which it won't in my lifetime, will it?

[QUOTE=gymno98;1638233393]And in general do you see a purpose in rubber or urethane coated plates? Or is simple cast iron the way to go?
I'll probably store the weights in my garage and take them out when I'm training.[/QUOTE]

Everyone has different wants/needs. I have mostly PU plates with a few iron plates. Eventually, I'll go all PU, but I only buy plates used and haven't picked up enough yet to ditch all the iron.

[QUOTE=Duplicitous;1638245143]Everyone has different wants/needs. I have mostly PU plates with a few iron plates. Eventually, I'll go all PU, but I only buy plates used and haven't picked up enough yet to ditch all the iron.[/QUOTE]

Does PU really degrade quickly in sunlight? I mean sure rubber does degrade quickly when exposed to sunlight but PU? I was always under the impression that PU is undegradable.

[QUOTE=gymno98;1638247043]Does PU really degrade quickly in sunlight? I mean sure rubber does degrade quickly when exposed to sunlight but PU? I was always under the impression that PU is undegradable.[/QUOTE]

The color will degrade quickly in direct sunlight. Structurally, it will hold up for awhile with the specifics of "how long" dependent on the quality of the PU.

[QUOTE=Duplicitous;1638252953]The color will degrade quickly in direct sunlight. Structurally, it will hold up for awhile with the specifics of "how long" dependent on the quality of the PU.[/QUOTE]

So it makes more sense to get the cast iron plates then because they are cheaper and probably last longer than PU in outdoor conditions even though they rust but rust isn't going to decrease the weight that fast.

If PU degrades you can't really fix it so you're stuck with uncoated cast iron plates that don't weigh as much as with the PU coating. Cast iron can be painted.

Is that right?
How long is cast iron going to last approximately in outdoor conditions before loosing 10% of its weight?