A sales rep working for a major paint producer, recently told me this story:

Our Company was not named in the project specs. The contractor submitted a substitution request to use our products, and our brand's reputation made it easy to get a change approved by the architect.

A few months later, the contractor called asking for help. The spec said to sand surfaces lightly between coats. This is a reasonable requirement with most brands of paint since sanding typically improves adhesion.

However, the contractor was using our newly introduced line that was especially formulated to adhere without sanding, and we had plenty of test data to substantiate the claim. In fact, our product literature recommends against sanding. The spec clearly said to follow the manufacturer's application instructions, yet the owner's rep still insisted on sanding between coats as specified.

The contractor had paid a premium for a labor saving product, but still had the expense of sanding.

The sales rep felt the owner's inspector was being unreasonable. The conflict could have been avoided if the request for substitution had disclosed how the proposed product affected all the specification requirements. Too often, a substitution request deals with Part 2 - Products requirements, without addressing Part 1 - General and Part 3 - Execution of a spec section.