Offset Printing Chemicals for CTP and PS Plates
Last updated: October 2026
Quick answer: The core offset printing chemicals in a plate room are plate developer, plate gum (finisher), baking gum and plate cleaner. CTPPress manufactures CTP and PS developer in our own factory and matches it to our plate grades; plate cleaner, baking gum and plate gum are supplied with our partner factories, so you can order the whole plate-room set with your plates.
Key takeaways
- Developer, gum and cleaner each do a different job; none of them can replace another.
- We make CTP and PS developer in-house for our thermal, CTcP and PS plate grades.
- Plate cleaner, baking gum and plate gum are supplied with our partner factories and shipped with your plate order.
- Chemistry must be matched to the plate grade, not chosen on price alone.
- Processless plates skip the developer, but still need the right cleaner on press.
Most printers think of offset printing chemicals as pressroom items: fountain solution, blanket wash, ink. This page covers the other half, the plate-room chemistry that turns an imaged plate into a press-ready one and keeps it clean once it is mounted. If you buy plates from us, ordering the matching developer, gums and cleaner in the same shipment removes one of the most common causes of plate problems: chemistry from one supplier fighting a coating from another, with each supplier blaming the other.
Which offset printing chemicals does a plate room need?
A typical plate room running CTP plates or conventional plates uses four product families. The table shows what each one does and where it comes from in our supply.
| Chemical | What it does | When it is used | Supply |
|---|---|---|---|
| CTP / PS developer | Removes the non-image coating after exposure | In the processor, every plate | Made in our factory |
| Plate gum (finisher) | Protects the non-image area from oxidation, fingerprints and dust | Gum section of the processor or by hand | Supplied with our partner factories |
| Baking gum | Protects non-image areas during baking | Before the plate goes into the baking oven | Supplied with our partner factories |
| Plate cleaner | Removes scum, dried ink and light oxidation | On press or in the plate room | Supplied with our partner factories |
Fountain solution, blanket wash and press washes are outside this range; buy them from your pressroom supplier.
CTP and PS plate developer
Printing plate developer is the one chemical we manufacture ourselves, because it is the one most tightly linked to the plate coating. We produce thermal plate developer for our single-layer and double-layer thermal plates, and PS plate developer for positive PS and single-layer CTcP plates. Each is formulated and tested against our own plate grades, so the processor settings in the grade TDS work as written.
The usual complaint we hear is “background tones after the developer gets old.” That is a replenishment and monitoring problem, not a plate problem. Our CTP developer guide explains replenishment, temperature and conductivity, and how to tell when a bath is exhausted.
Plate cleaner for press and plate room
An offset plate cleaner removes scum, dried ink and light oxidation from the non-image area, for example when plates scum after a press stop. It is supplied with our partner factories in two types:
- On-press cleaner, for quick cleaning without unmounting the plate.
- Plate-room cleaner, for restoring stored or oxidised plates before use.
The wrong cleaner can attack the image area of some coatings, so check compatibility before use. See our plate cleaner page for on-press vs off-press types and safe use.
Baking gum and plate gum (finisher)
Plate gum, also called plate finisher, is a thin protective layer applied after development. It keeps the hydrophilic non-image area clean and water-receptive while plates wait for the press. Most processors apply it automatically in the gum section.
Baking gum is a different product. It is applied before a plate is baked, to stop the non-image area from being contaminated during the heat cycle and to make it easy to wash out on press. Use it only on plates that will go into a plate baking oven; normal plate gum is not designed for baking temperatures. Both gums are supplied with our partner factories and can be shipped with plates and developer in one consignment.
- Plate gum: every plate, after development, unless the processor already applies it.
- Baking gum: only for baked plates, before the oven.
- Do not mix the two, and do not dilute beyond the instructions on the label.
How to match chemicals to your plates
Chemicals are not interchangeable commodities. A developer that works for one thermal plate can over-develop another; a strong cleaner that suits a baked plate can weaken an unbaked image. Buyers want one supplier for plates and chemistry, but often raise fair objections: local chemistry is cheaper, shipping liquids is expensive, or “we already have a developer that works.” Those are reasonable. Our practical approach:
- Tell us which plate grades you run, from our thermal CTP plates, CTcP plates or PS plates ranges.
- If your current local developer gives stable results, run a trial with our plates in it first; we will advise if the chemistry is a mismatch.
- If you change developer, change it with a clean tank and fresh replenisher, never by topping up one brand with another.
- Combine liquids with a plate order so they ship in the same container, which keeps freight per unit reasonable.
Processless plates are the exception: processless CTP plates need no developer, but they still need a cleaner that is approved for unbaked processless coatings. Developer and gum also have to suit your processor; see our CTP plate processor range. Note that we do not supply negative PS plates or double-layer CTcP plates, so we do not stock developers for those either.
When in doubt, our technical support team will check your processor settings against the plate TDS before you change anything.
FAQ
What chemicals are used in offset printing?
In the plate room: developer, plate gum (finisher), baking gum and plate cleaner. In the pressroom: fountain solution, blanket and roller washes and ink. CTPPress supplies the plate-room chemicals.
What is the difference between plate developer and plate gum?
Developer removes the non-image coating after exposure. Plate gum is applied afterwards to protect the developed non-image area from oxidation, fingerprints and dust until the plate is on press.
What is baking gum used for?
Baking gum is applied before a plate is baked. It protects the non-image area during the heat cycle and washes off easily on press. Normal plate gum is not a substitute.
Can I use any developer with my CTP plates?
No. Developer chemistry, temperature and replenishment must match the plate grade. Thermal, CTcP and PS plates each need the developer type named in the grade TDS.
Do processless plates need chemicals?
Processless plates need no developer, but they still need a compatible plate cleaner on press. Check the cleaner is approved for unbaked processless coatings.
Ordering plates and chemistry together? Request a quote and send your plate grades, processor type, monthly plate volume and the chemicals 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.
