Thank you, Wirecutter. I read the whole thing.
“Michael Sheafe, who specializes in vintage toaster repair, provided us with several used (but still-operational) toasters dating from about 1918 through the 1930s. We sent those, along with the Cuisinart CPT-122 Compact Plastic Toaster and the Breville BTA720XL Bit More Toaster (two picks from our guide to the best toaster), to students in the Department of Materials Science and Engineering at The Ohio State University. To help us determine exactly why slot toasters aren’t what they used to be, the students (under the guidance of associate professor Elvin Beach) broke apart each toaster for comparative analysis.”