Before going into mass production of a product, it is always wise to request pre-production samples for approval. It is important to note, when placing future orders from suppliers and manufacturers, that variations in your product order may occur between pre-production samples and mass production of the product.
Many times, across a diverse array of sectors and industries, manufacturers use different methods to produce pre-production samples and mass-produced products. The sample process is a little more intricate because they are only creating a few products at a time. Therefore, the team creating the samples can spend more time on the production process and overseeing each sample whereas, the mass production team cannot watch every single mass-produced product, especially if a large amount is being manufactured.
As a result, there are bound to be variations in the product if it is mass produced. This is part of the production process. This is also dependent on the type of product ordered. Natural materials make it more difficult for products to be exactly the same, this is quite common with fabrics and stitching.
Delaying the production process due to variations in product consistency can be a very costly exercise for both you and the manufacturer. Take each order as unique, assess the variations and determine whether or not it is worth your time and effort to remanufacture the products.