One advantage with copper lined with stainless steel is you can go hotter than tin as the tin will melt. I roasted bones in my large copper stainless steel lined at 460 degrees which I thought worked great. It might be a little iffy with tin lined.
I am still in debate about the long run on whether I want the hassle of copper. I plan not to baby these copper pans.
So, for shrimp and scallops you prefer 3mm? I know not about cooking with copper.
I am a really big fan of copper and tin. Warning, I'm about to go off the deep end
I think people overdo the concern about tin melting. The only way to melt tin is to use it "high and dry" which means high heat and dry (no water, or oil, or cooking fluid). If there is any sort of water/oil then it will keep the heat down over the whole pan (even if the burner is on max).
The melting point of pure tin is 450f, but again if there is anything in the pan to help absorb the heat, then there is really no concern of melting. But once tin gets "seasoned" it will darken (there are several things going on here, I'll post the full article below), but something called an intermetallic layer forms, which raises the melting point of tin to somewhere in the 780-1250f range. Someone could melt it, but once seasoned, they really have to try.
https://www.vintagefrenchcopper.com/2020/01/a-little-science-about-copper-and-tin/
For comparison, teflon (in teflon coated pants) starts to break down around 500f and is burnt by 650f. So tin really isn't any more of a concern for melting than teflon is burning. Once the tin is seasoned, it's even less of a concern. But accidents can and do happen (such as forgetting a pan on the stove), and the nice thing is with tin, it can be repaired. Have it "retined" and it's literally as good as new.
This is also why people often recommend putting a drop of cooking oil or butter in a copper pan as it preheats. The oil/butter will burn and give you an alarm (burning smell) before the tin melts. And tin doesn't need to be preheated like stainless steel to be non stick. It also comes up to temperature shockingly fast, so again, no need to preheat. Put it on the stove, drop in your oil/butter and your cooking/frying almost right away.
If someone overheats a copper and stainless pan, the stainless can and will delaminate. I'm not sure what temperature this happens at, but it does happen. But like burning a teflon pan, or melting tin, someone does need to muck up and forget about it on the burner. Unfortunately once delaminated it can't be repaired and needs to be replaced. I'm not sure if Falk or Maviel will warranty them from accidental overheating, as this type of delimitation is not really "normal use". Although I also wouldn't be surprised if either company did warranty them anyways, from what I hear both are first rate companies to deal with.
The only downside of tin is needing to treat it nice. Basically treat it like teflon. No metal utensils, don't overheat it, don't use an abrasive scrubby when cleaning. But if someone accidentally mucks it up, unlike a teflon pan, it can be fixed.
Now, after all this is said and done, my frying pans are silver lined not tin. Silver is even a better heat conductor than copper, and it's melting point is over 1200f even when brand new. I decided to splurge and get silver lined copper frying pans. I specifically did so I can try toast seeds nuts in my pan, as I do this often. I could use stainless steel for this, but for even toasting I wanted a pan with more even heating. If it wasn't for dry toasting seeds and nuts I would have stayed with tin lined pans.
Ok, that got long. If you're still following along, kudos to you.
Lastly I'll address the 3mm thickness. Once you reach 3mm thick you get a very even heat across the bottom of the pan. This is great for things like delicate sauces, and sauting. Everything will brown near perfectly uniformly. Which is really nice for things like shrimp and scallops.
3mm is really the sweet spot, as even large pans will stay near have near perfect heat uniformity (like large12.5" sauté pan), but it's not so thick that it looses its responsiveness. By the time you're at 4mm the responsive does drop off, nor do you notice any additional evenness when cooking. Here is a good article about:
https://www.vintagefrenchcopper.com/buyers-guide/buying-and-selling-online/what-should-i-buy/
As a whole, the VFC site is really helpful. About half of my copper is "no name", but is 3mm thick, so I still get all the benefits. About 80% of my copper is vintage. Much of it was out of France, and I had it redone there before it was sent over. Cost wise I paid less than All-Clad D3, and near D3 factory outlet sale prices. So it doesn't have to be expensive if you bargin hunt. All and all, I love it.
But... the final but... it will tarnish. If you want perfect looking copper, the upkeep is annoying. I prefer the mild dark patina anyways, with less shine, so I'm happy. I use copper brill every so often to keep in the medium dark copper range. Still looks clean and pretty, but not use it as a mirror shinny. I'm happy
Okay, if you made it this far, I should buy you a beer or a bottle of wine!
