How to Identify Antique Picture Frames

Okay, I need to help the user by providing a comprehensive guide on how to identify antique picture frames. Let me start by understanding the query. The user is researching this topic in depth for an article and wants detailed information across eight specific aspects. First, I’ll go through each of the search results provided to gather relevant information. The search results include various sources like guides from framing companies, historical background, types of frames, factors affecting value, authentication methods, market trends, buying/selling tips, and care instructions.