I suspect that the size of what is sold as any mulch depends on the company creating the mulch as bark can be ground and passed through sieves of many different sizes even when described as "fine".
This website
http://www.hortmark.com/pine-b... indicates,
"Aged Pine Bark Fines are made to a smaller size - we process it to 1/2" for special uses. Landscapers use Aged Pine Bark Fines as decorative mulch around small plants such as annuals and perennials.
Many horticulturists use Aged Pine Bark Fines as a soil conditioner. Used as a topdress or incorporated directly into soil mixes, Aged Pine Bark Fines makes a stable, long lasting soil conitioner."
This one,
http://greendellmulch.com/prod... indicates,
"Pine Bark Fines Mulch", "This mulch consists of bark from pine trees and has a particle size of approximately 3/4”. Pine mulch is recommended to use around plants that require a high acidic environment and may also be used as a soil amendment."
This one,
http://lowe-products.com/produ... indicates,
"Our pine fines mulch is an all bark product which is aged through composting. It is then processed through a 3/8″ screen. It is 100% natural with no additives which could harm the environment or humans. This product is an excellent soil amendment and potting medium."
Three different maximum sizes for pine fines of 3/4", 1/2" and 3/8" from three different companies. I expect that there may be other companies that grind their pine fines to smaller maximum sizes.
