Why use a liner at all? An empty drum that's clean inside is easier to reuse or get rid of than one that is contaminated with leftover product. It's important to get all the raw material out of the drum.
The most common liners are bags made of low density polyethlyene film. Flat bags are just like giant sandwich bags. Advantage: Lowest cost. Problem: the straight seam at the bottom makes folds and pockets as it conforms to the round drum bottom, so material can get trapped and is difficult to remove.
Round-bottom bags have a circular bottom seam that fits your drum perfectly. Your product inside the drum comes out much easier. There's less strain on the bag too, so there's less chance of a leak. Round-bottom bags are much stronger for use with pumps and floater plates.
Note: Due to fluctuations in the resin market, we are unable to guarantee the same pricing as is listed on the website at the time you place the order. If there is an increase in pricing, we will notify you for your approval before processing your order.