Last updated: October 2026
Quick answer: The main types of CTP plates are thermal plates (single-layer and double-layer, imaged at 830 nm), processless thermal plates that develop on press, CTcP plates imaged by UV platesetters, violet photopolymer plates for violet platesetters, and polyester plates for small offset. Your platesetter’s laser decides the plate family; run length, ink and chemistry then decide the grade.
Key takeaways
- Start from your platesetter: thermal, UV (CTcP) and violet systems each need their own plate family.
- Within thermal, single-layer plates cover most commercial work; double-layer plates add chemical resistance for UV inks and demanding jobs.
- Processless plates remove developer and processor but trade off image contrast and baking.
- Each plate type is a trade-off between cost, chemistry, run length and handling — there is no single best plate.
Buyers often tell us there are too many plate names and every supplier says something different. The result is real cost: the wrong plate choice wastes press time, and chemistry costs keep going up. This guide gives a simple comparison of plate types, explains how each one is imaged and processed, and shows how to find the plate that matches your platesetter and press. We manufacture most of the plate types below in our own factory, and we say clearly where we do not supply a product.
What are the main types of CTP plates?
Computer-to-plate (CTP) means the image is written directly onto the plate by a laser or UV light source, without film. Plates are grouped by how they are imaged:
- Thermal plates — imaged by infrared lasers at 830 nm. Includes single-layer, double-layer and processless grades.
- CTcP (UV) plates — imaged by UV light on a CTcP platesetter; chemically close to conventional PS plates.
- Violet photopolymer plates — imaged by violet laser diodes; negative-working.
- Polyester plates — film-base plates for small offset and duplicator presses, often laser-printer imaged.
Many buyers think the plate type is a free choice based on price. In practice your platesetter laser decides the plate family, then run length, ink and chemistry decide the grade. For background on the workflow itself, see what CTP printing is.
Thermal CTP plates: single-layer and double-layer
Thermal plates are the most widely used type for commercial and packaging printing. The 830 nm laser changes the solubility of the coating, and the exposed areas are removed in an alkaline developer (positive-working). Because thermal coatings are not sensitive to normal room light, handling is simple.
Single-layer thermal plates have one imaging layer. They cover most commercial, book and general packaging work, are economical, and many grades can be baked for longer runs.
Double-layer thermal plates add a chemically resistant bottom layer under the imaging layer. That improves resistance to UV inks, aggressive press chemicals and washes, and gives higher run-length potential. They cost more and need tighter developer control.
We manufacture both single-layer and double-layer thermal CTP plates. Exact run length and baking behaviour are on each grade TDS.
Processless thermal plates
Processless plates are thermal plates that need no developer and no processor. After imaging at 830 nm, the plate goes straight to press, where fountain solution and ink remove the non-image coating in the first sheets. Benefits: no chemistry, no processor maintenance, no developer waste. Trade-offs: the image is low-contrast and hard to inspect before press, plates are not baked, and run length and UV-ink compatibility are set by the grade.
A common objection is that processless plates cannot handle real production. For short and medium runs within the TDS limits they handle it well; for very long or UV-ink runs a processed, baked plate is usually safer. Read more on our processless CTP plates page.
CTcP (UV) plates
CTcP — computer-to-conventional-plate — plates are imaged by UV light on a UV CTcP platesetter. Chemically they are close to positive PS plates, so they process in a similar developer and are economical. They are popular with printers moving from film and PS plates to CTP, and with newspaper and commercial printers using UV platesetters.
We manufacture single-layer CTcP plates. We do not supply double-layer CTcP plates. UV CTcP platesetters are supplied with our partner factories — see our UV CTP machine page.
Violet photopolymer plates
Violet plates are negative-working photopolymer plates imaged by a violet laser. They are handled under a yellow safelight and usually processed with preheat, prewash, development and gumming. Violet systems were widely installed in newspaper printing, and many still run well today.
We manufacture violet photopolymer plates for printers who keep their violet systems running; violet platesetters are supplied with our partner factories. Details are on our violet CTP plates page.
Polyester plates for small offset
Polyester plates are not aluminium CTP plates in the strict sense, but buyers often compare them. They use a polyester film base, are usually imaged on a laser printer or small-format imager, and run on small offset and duplicator presses. They are economical for short one- and two-colour jobs; long runs and tight multicolour register still need aluminium. See our polyester printing plates.
For completeness: conventional PS plates are exposed through film, not by CTP. We manufacture positive PS plates; we do not supply negative PS plates.
Comparison table of CTP plate types
| Plate type | Imaging | Processing | Handling light | Typical strengths | Typical limits | Supplied by us |
|---|---|---|---|---|---|---|
| Single-layer thermal | 830 nm thermal platesetter | Developer, rinse, gum; bakeable grades | Room light | Versatile, economical, stable | Lower chemical resistance than double-layer | Yes, own-made |
| Double-layer thermal | 830 nm thermal platesetter | Developer, rinse, gum; bakeable grades | Room light | UV inks, aggressive chemicals, longer runs | Higher cost, tighter developer control | Yes, own-made |
| Processless thermal | 830 nm thermal platesetter | None — develops on press | Room light per TDS | No chemistry, no processor | Low image contrast, not baked | Yes, own-made |
| Single-layer CTcP | UV CTcP platesetter | Developer, rinse, gum | Yellow safelight | Economical, easy step from PS | UV-sensitive handling | Yes, own-made |
| Double-layer CTcP | UV CTcP platesetter | Developer, rinse, gum | Yellow safelight | Higher chemical resistance | — | Not supplied |
| Violet photopolymer | Violet platesetter | Preheat, prewash, develop, gum | Yellow safelight | Fast imaging, newspaper workflows | Safelight and preheat control | Yes, own-made |
| Polyester | Laser printer or small imager | Usually none | Normal light | Low cost for short runs | Short run, limited register | Yes, own-made |
All aluminium types are commonly offered in 0.15, 0.20, 0.25 and 0.30 mm gauges. Run length, sensitivity and resolution figures belong on each grade TDS with its test conditions, not in a general comparison.
How to choose the right plate type
One plate type is not best for every printer; each plate type is a trade-off between cost, chemistry, run length and handling. Work through these questions in order:
- Which platesetter do you have? Thermal, UV or violet decides the plate family. Check our CTP plate compatibility guide.
- What are your typical run lengths? Short runs open the door to processless plates; long runs favour bakeable thermal grades.
- What inks and chemicals do you use? UV inks and aggressive washes point to double-layer thermal plates.
- How much does processing cost you? If chemistry and processor upkeep are a burden, compare processless against processed plates on total cost.
- What gauge and size does your press need? See the plate size chart.
Some buyers worry that the cheapest plate is always good enough, or that changing plate type means changing the whole workflow. Neither is quite true: the lowest cost per plate without losing quality comes from matching the grade to the job, and moving between grades within the same family (for example single-layer to double-layer thermal) usually needs only developer and exposure adjustments. Price factors are explained in our CTP plate price guide.
FAQ
What are the different types of CTP plates?
The main types are thermal plates (single-layer and double-layer), processless thermal plates, CTcP (UV) plates, violet photopolymer plates and, for small offset, polyester plates.
What is the difference between single-layer and double-layer thermal plates?
Single-layer thermal plates have one imaging layer and suit most commercial work at lower cost. Double-layer plates add a chemically resistant bottom layer for UV inks, aggressive washes and longer runs.
What is the difference between processless and processed CTP plates?
Processed plates are developed in a processor and give a clear image that can be inspected and often baked. Processless plates go straight from the platesetter to press and develop there, removing chemistry but with low image contrast and no baking.
What is the difference between CTP and CTcP plates?
CTP usually refers to thermal or violet laser-imaged plates. CTcP plates are imaged by UV light on a UV platesetter and are chemically close to conventional PS plates.
Are violet CTP plates still used?
Yes. Many newspaper and commercial printers still run violet platesetters, and violet photopolymer plates keep those systems productive.
Which CTP plate is best for my printing house?
Start from your platesetter type, then choose the grade by run length, ink type and how much processing chemistry you want to manage. A trial on your own press confirms the choice.
Not sure which plate type fits your platesetter and press? Request a quote — send your platesetter, press, plate size, gauge, ink type and monthly volume. 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.
