No, it's a good question. So leather bags used to be made where they would fold or roll the leather at the edges, so the edges would tend to wear out and get holes or extra dirt. The edges looked something like this:
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Edgecoat is where they apply some sort of plastic product (I think it is a liquid that hardens) to protect the edges. What I meant by edgecoat matching is that the color of it matches (or is close to) the leather like this:
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I think it looks sloppy when they use a generic brown or black color on light leather bags, or if the coating on the edge is uneven like this:
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It's something they do just because it's cheaper to use one type of edgecoat then buying a new batch for each color leather they make. But I think this practice is unacceptable when one is paying a lot of money for a bag. For example this outlet charm has three types of edgecoat and it was like $20 so it can't be that hard or expensive to match the edgecoat properly:
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I think I would rather they just leave the edges bare if they are going to do a poor edgecoat job, but it's a pet peeve of mine. Most of the new bags I've purchased recently have been black because the edgecoat naturally tends to match. Many of the rehabs on the
Coach rehab thread have applied edgecoat to their own bags where it has chipped off or to fix an edge.