Film problems
Why bubbles and white spots appear in plastic film — moisture or processing?
A practical look at the causes of bubbles and white spots in film, and how to start diagnosis before making big changes.
Bubbles and white spots are among the most common defects in plastic film, and they usually trace back to moisture in the material or instability in processing. When moisture reaches the melt stage it turns to vapor inside the melt, showing up as a bubble, a small void, or a white spot in the finished product.
Recycled materials and material stored for a long time or in a humid place are more prone to the problem, because they absorb moisture from the air. Variation in the material source from batch to batch also makes the result inconsistent even when the settings are unchanged.
Before changing anything major, start with a simple review: how and where is the material stored? Is there a clear difference between batches? Do bubbles increase with a particular material or source? These observations save a lot of diagnosis time and separate a moisture problem from a processing one.
If moisture is the likely cause, a desiccant masterbatch helps absorb limited moisture during processing and reduce the related defects. It is not a full replacement for drying with highly hygroscopic materials or high moisture levels, and the result depends on the material type and processing conditions.
The best way to decide is to test a sample on the same line and the same material before committing to a large order, so you see the result under your real conditions rather than in theory.