Effective cleaning of photopolymer printing plates is one of the pillars of achieving high quality and repeatability of flexographic printing. A properly conducted cleaning process includes not only the use of specialized detergents, but also a thorough rinsing with water. It is this last step that often determines the durability and condition of the printing plate after printing.
Tripartite interaction - underbooth the process
Three key components interact during flexo die cleaning:
photopolymer printing plate, made of polymers and elastomers, among other materials,
Printing inks containing various coloring and solubilizing substances,
A cleaning chemical that contains compounds capable of dissolving printing inks.
The printing inks and the cleaner work together - the chemicals dissolves the printing inks residue. However, both components also affect the matrix itself. And this is where the key aspect of rinsing comes in.
Solvents vs. structure of polymers
Polymers that make up photopolymer plates are large molecules composed of repeating units—monomers—held together by intermolecular forces. Chemical solvents, present in both inks and detergents, can weaken these forces, causing:
swelling,
Micro-cracks and delamination,
Pitting and surface damage,
Crumbling and permanent degradation of the printing plate structure.
While not every polymer is easily dissolved, many show sensitivity to specific dissolving compounds - and these are commonly present in flexo inks. Depending on the type of ink, its formulation and the nature of the printing plate itself, irreversible structural changes to the material can occur.
The role of water flushing - protection and hygiene of the process
To minimize the risk of damage to the printing plate, it is essential to use the final cleaning step - water rinsing. It allows:
neutralize residual solvents that could further affect the polymer,
Remove pigment fines and residues of abrasive printing inks components,
extend the life of the printing plate, reducing wear and tear over time,
raise the hygienic boothard of the entire process, which is particularly important when printing food packaging.
It is worth noting that not all printing plate damage is immediately apparent. Prolonged exposure to aggressive chemicals without proper rinsing can lead to gradual degradation, the effects of which are noticeable only after many production cycles.
A proper cleaning process for photopolymer printing plates must include a thorough rinsing with water. This is a simple but extremely effective action that:
protects the printing plate structure,
Increases the repeatability of printing,
Extends the life of printing tools,
fits in with safety boothards, especially in the food industry.
At Print Systems , we promote solutions that make a real difference in the quality and stability of the flexo printing process. Proper washing is not just about cleanliness - it is a strategy for long-term quality maintenance.
