Plate Cleaner for Offset CTP, CTcP and PS Plates
Last updated: October 2026
Quick answer: A plate cleaner removes scum, dried ink, gum residue and light oxidation from the non-image area of an offset plate so it takes water again and prints clean. CTPPress plate cleaner is supplied with our partner factories in on-press and off-press types. We advise which type suits your thermal, CTcP or PS plates and provide the SDS on request.
Key takeaways
- Plate cleaner restores the non-image area; it is not a blanket wash or a developer.
- On-press cleaner is for quick cleaning on the cylinder; off-press cleaner is for restoring plates in the plate room.
- The cleaner must be compatible with the plate coating, especially for unbaked thermal and CTcP plates.
- Always work from the safety data sheet (SDS): gloves, ventilation and correct storage.
- Our plate cleaner is supplied with our partner factories and can ship with your plate order.
Every pressroom has the same moment: the press stops for a paper change or a breakdown, and when it restarts the plates start scumming. Or a plate comes out of storage with a grey haze of oxidation. A good plate cleaner fixes these without remaking the plate. A bad one, or the wrong one, fixes the background and quietly weakens the image area, so the job prints fine for an hour and then starts losing highlight dots. This page explains how to choose and use an offset plate cleaner for CTP plates and conventional plates.
What does a plate cleaner do?
On an offset plate the non-image area must stay hydrophilic (water-loving) so it repels ink. Ink, dried fountain solution, paper dust, old gum and oxidation of the aluminium all reduce that water receptivity. A plate cleaner dissolves or lifts these contaminants and leaves a clean, water-receptive surface. Many cleaners also leave a light protective film, similar to gum.
| Problem on the plate | Typical cause | Can plate cleaner help? |
|---|---|---|
| Scum or toning after a press stop | Ink drying on the non-image area, fountain balance lost | Yes, on-press cleaner |
| Dried ink at the end of a shift | Plate left inked without gumming | Yes, then re-gum |
| Grey haze on a stored plate | Light oxidation, poor gumming or humid storage | Often, with an off-press cleaner |
| Background not clean on a new plate | Under-development or tired developer | No; fix the processing first |
| Image area wearing or blinding | Wrong cleaner, aggressive washes, worn plate | No; check compatibility and run length |
If a new plate is dirty straight out of the processor, the cause is processing, not the press. Check your CTP developer condition before reaching for the cleaner.
On-press vs off-press plate cleaner
On-press plate cleaner is used with the plate mounted on the cylinder. It works quickly, is usually milder, and is formulated to rinse off with fountain solution so printing can restart without extra steps. Use it when plates start scumming after a stop or when dried ink needs to come off between jobs.
Off-press plate cleaner (sometimes called plate-room cleaner or plate restorer) is used on the bench. It is stronger and is meant for plates that have been stored, oxidised lightly, or need cleaning before a reprint. Some off-press grades are mildly abrasive; those are for durable or baked plates only.
- Choose on-press cleaner if you want to clean plates without restarting the job.
- Choose off-press cleaner for stored plates and reprints.
- Avoid abrasive grades on unbaked thermal, CTcP and processless plates unless the plate TDS allows them.
How to use plate cleaner safely
Plate cleaners contain solvents, acids or both. Your safety officer will ask for the SDS before the product goes into the pressroom, and we provide it on request with the quotation. General steps:
- Read the SDS and the label. Wear chemical-resistant gloves and eye protection; keep the area ventilated.
- Shake the container. Apply a small amount to a clean sponge or lint-free pad, not straight onto the plate.
- Rub the non-image area with light, even pressure. Avoid long contact on solids and fine highlight areas.
- Rinse with water (off-press) or let the dampening system take over (on-press, per the product label).
- If the plate will stand, apply a thin layer of plate gum and buff dry.
- Close the container, store away from heat and direct sun, and dispose of rags and waste as the SDS and local rules require.
Test first. Before using any new cleaner across a whole job, try it on the edge of a scrap plate of the same grade and check that the image area is not attacked.
Compatibility with thermal and CTcP plates
A common belief is that any solvent works as plate cleaner. It does not. Strong solvents and aggressive cleaners can soften or remove the image coating of unbaked plates. That is why the image area gets weak after cleaning in some pressrooms: the cleaner is doing its job on the background and damaging the image at the same time. The cleaner must be compatible with the plate coating and used per the SDS.
- Thermal CTP plates: use a cleaner approved for thermal coatings, especially if the plates are not baked or run with UV inks.
- CTcP plates and PS plates: use a mild, conventional-plate cleaner; avoid strong solvent blends.
- Baked plates: more resistant, and the main candidates for off-press or mildly abrasive cleaners.
- Processless plates: use only cleaners approved for processless coatings.
If you are not sure the cleaner suits your thermal plates, send us the plate grade and the inks you run; our plate technical support team will advise.
Ordering plate cleaner with your plates
Our plate cleaner is supplied with our partner factories, not made in our plate factory, and is shipped together with plates and developer so one supplier answers for the whole plate set. The usual objection is that local cleaner is cheaper. That can be true; if your local product works on our plates, keep using it. Ordering ours makes sense when you want one source for plates and chemistry or cannot find a compatible cleaner locally. Pack sizes, MOQ, price and lead time are confirmed in the quotation. See the full offset printing chemicals range for developer, baking gum and plate gum.
FAQ
What is plate cleaner used for in offset printing?
Plate cleaner removes scum, dried ink, gum residue and light oxidation from the non-image area of an offset plate, so the plate takes water again and prints clean.
How do you clean an offset printing plate?
Put a small amount of compatible plate cleaner on a sponge, rub the non-image area evenly, rinse with water or let the dampening system take over, then gum the plate if it will stand. Follow the SDS for gloves and ventilation.
Can plate cleaner damage a CTP plate?
Yes, the wrong cleaner can. Strong solvents or abrasive cleaners can attack the image coating of unbaked thermal, CTcP or processless plates. Use a cleaner approved for your plate type and test it on a scrap plate first.
What is the difference between on-press and off-press plate cleaner?
On-press cleaner is milder and used with the plate on the cylinder to clear scum quickly. Off-press cleaner is stronger and used on the bench to restore stored or lightly oxidised plates.
How do you remove oxidation from an offset plate?
Light oxidation can usually be removed with an off-press plate cleaner, followed by a rinse and a fresh coat of plate gum. Heavy oxidation often cannot be fully reversed, so prevent it with correct gumming and dry storage.
Need plate cleaner with your next plate order? Request a quote and send the plate grades you run, on-press or off-press use, the inks you print with and the quantity you need. Or request trial plates / contact us.
Disclaimer: values on this page are typical and for reference only; final specifications, MOQ, price and lead time are subject to the grade TDS and the quotation.
