Choosing offset printing chemicals starts with the deposit, ink and press component. Washing, descaling and surface care solve different problems. Learn which checks help you select the appropriate product.
Why does a print shop need auxiliary chemicals?
Ink, paper dust, coating residues and water deposits gradually change the surface of the rollers. Over time, the roller loses its ability to accept and release ink. Streaks appear, unstable ink-water balance and longer start-up after washing.
Therefore, auxiliaries help keep the inking system, wetting system, blankets and fountain solution circulation clean. However, each preparation has a specific use. Therefore, do not replace the descaling agent with an ordinary wash and do not use reclaimed cleaner without checking the type of rubber.
How do you choose a wash for the ink and press?
First recognize the contamination: ink, calcium deposits or contamination of the wetting system. Then determine the type of ink and surface material. Only then choose the preparation and method of application.
| Problem | Agent type | What should you look out for? |
|---|---|---|
| Color change and normal washing | Roller and blanket wash | Dissolving ink, miscibility with water, manual or automatic method. |
| UV ink or mixed system | UV wash | Compatibility with EPDM, NBR/PVC and machine manufacturer’s recommendations. |
| Glaze and calcium deposit | Descaling agent or deglazer | After treatment, rinse the rollers thoroughly according to the technical data sheet. |
| Sediment on the dampening roller | Agent for dosing and dipping rollers | Do not use random solvent or sharp instrument. |
Choose a wash for conventional or UV inks and the type of rubber. Use only a preparation compatible with this elastomer on EPDM. At WIT, we will help you check compatibility with your machine.
Washing rollers step by step
Consider the list below as a process control. Manual and automatic washing require different procedures. Work on the machine only in the mode permitted in its manual.
- Remove any remaining ink from the machine according to the manufacturer’s procedure.
- Adjust the amount of wash to the width of the assembly and the degree of dirt.
- Perform the washing cycle in the mode recommended by the machine manufacturer. Do not increase the pressure to speed up washing.
- Drain the dissolved ink and observe whether the surface of the rollers regains an even appearance.
- If necessary, perform a second rinse step. Do not leave any residue on the rubber.
- Remove any remaining agent according to the technical data sheet. Check the manufacturer’s instructions for the conditions for preparing the rollers for parking.
Do not mix random preparations as they may react with each other. The mixture may also change the viscosity or impair surface wetting.
How to remove scale and glaze from rollers?
Calcium deposits and paper coating residues may clog the roller surface. Then an ordinary ink wash dissolves the ink, but does not restore proper ink absorption. Then use a descaling agent or deglazing paste according to the manufacturer’s instructions.
After descaling, perform the rinsing indicated in the card of the specific preparation. Calcium Deglazer requires rinsing with water. Plan deep cleaning according to water hardness, paper type and machine load.
What to do to keep the rollers in good condition?
- Clean the rollers regularly before the residue hardens.
- Control water hardness and parameters of the fountain solution.
- Select the preparation according to the type of rubber, ink and blanket used.
- Before parking, clean the rollers and follow the manufacturer’s recommendations for drying or protection.
- Do not use a knife, scraper or rough cloth on the rubber surface.
- Store the removed rollers without putting pressure on the tread, away from light and high humidity.
For Böttcher dampening rollers intended for daily cleaning, follow this schedule. Avoid sharp tools, random solvents and reclaimed products. It’s a simple routine that limits surface damage.
Auxiliary chemicals in the dampening system
The dampening system, on the other hand, requires separate inspection. The inking roller agent does not have to be suitable for the dosing roller or circulating tank. To clean the circulation, choose a preparation designed to remove sediments, dirt and biofilm in recirculation systems.
Check pH, conductivity, water hardness and recommended proportion of alcohol or substitute. Therefore, do not adjust the parameters “by eye”. Changing one ingredient can affect the ink-water balance and the behavior of the board.
When will a wash not solve the problem?
Still seeing streaks, uneven transfer or rapid glazing after washing? Check the pressure, hardness, wear and alignment of the rollers and the condition of the bearings. Chemistry will not repair deformed rubber or incorrect setting.
Compare the consumption of the preparation per wash and the downtime. The price per liter does not describe the entire cost. Moreover, an incompatible agent may damage the elastomer regardless of its price. If you are changing ink or supplier, ask for confirmation of compatibility.
Frequently asked questions
Is one wash enough for conventional and UV inks?
Don’t assume it. Some remedies support both applications, but others require a specific gum or a separate procedure. Check the technical data sheet.
How often should I use the descaling agent?
Determine the frequency based on the hardness of the water, paper and machine load. Regular prevention limits the build-up of deposits. Adjust the schedule to the preparation used and working conditions.
Can I clean the roller with a metal scraper?
No. Sharp and hard tools may damage the roller surface. Use the method and material described in the manufacturer’s instructions.
What data should be prepared for the selection of chemicals?
Check VARN printing chemicals and other printing chemicals.
Provide the machine model, ink type, roller material and name of the agent used. Describe the symptom and when it appeared. This data will distinguish a contamination problem from a material or setting incompatibility.