Why do air bubbles often appear in printing?(1)

Update:10 Feb 2020
Summary:

In the sample printing, a variety of printing problems […]

In the sample printing, a variety of printing problems will occur if you pay little attention to it, so printing is a meticulous task, and we need to be extremely careful in each of these steps. If we do not solve the problems on printed products in time, it will inevitably be considered as a defective product, which will not only damage the quality and quality of the printed matter, but also reduce the customer's trust and evaluation of the company. We must be extremely careful about all kinds of problems. So why are there bubbles and how can I avoid them?
In the sample printing, the reason why the substrate appears air bubbles on the ink is mainly reflected in the following aspects:
1. The substrate has poor pre-treatment, that is, the substrate has not been cleaned before, making its surface full of dust or oil stains.

www.dpiflex.com