What underpacking sheets do in the pressroom
Underpacking sheets sit between the cylinder and the blanket or plate packing to bring the press back to the right impression height. They are used when a cylinder needs adjustment after blanket changes, plate changes, wear, or a change in substrate thickness. In day to day work, the aim is simple: keep pressure even, reduce bounce, and help the print hold register without overloading the machine.
For offset printers in Johannesburg, Pretoria, Germiston and beyond, the right underpacking saves time during make-ready and prevents guessing with loose paper packs. It also helps when a job runs across different paper grades, from coated stock to board, where packing requirements can shift slightly. A consistent sheet gives the press team a repeatable starting point instead of a trial-and-error stack of scrap.
Sheet options, thicknesses and formats
We supply underpacking sheets in practical formats used by sheetfed and finishing teams. Common requirements include cut sheets for press setup, larger sheets for blanket packing, and pre-cut pieces for repeat jobs. Thickness control matters more than the label on the pack, so the focus should be on measured, stable material that stays true under pressure.
- Thickness options commonly used for plate and blanket packing, including fine adjustment grades
- Cut sizes for quick set-up on smaller presses and guillotines
- Larger sheet formats for full blanket cylinder coverage
- Single sheets or packs for job-specific adjustment work
- Materials suited to dry and humid pressrooms alike
Where a pressroom runs several machines, it helps to keep a standard range on hand rather than mixing old offcuts and improvised packing. That gives your operators a cleaner base to work from and reduces variation between shifts.
Where underpacking sheets work best
These sheets are used across offset litho, flexo support work, and print finishing environments where cylinder height must stay accurate. They suit packaging plants, commercial printers, label converters, and trade finishing shops that need controlled pressure on repeat production runs. In a city west operation or a nationwide dispatch setup, they are the sort of consumable that keeps machines productive without much fuss.
They are especially useful where jobs change often, because repeated blanket or plate changes can alter packing over time. If your team handles short runs, urgent reprints, or colour-sensitive work, the ability to correct packing quickly can make a proper difference. It is also useful for presses that see heavy daily use and begin to show wear at contact points.
- Sheetfed offset presses
- Blanket cylinder packing
- Plate cylinder adjustment
- Flexo support applications
- Finishing and pressure-sensitive setup work
Installation, setup and machine requirements
Underpacking sheets fit under the plate or blanket by hand. They are fitted manually during press setup or maintenance, usually by the operator, makeready technician, or service team. What matters is that the machine is isolated, the cylinder area is clean, and the required thickness is checked with proper measuring tools before the pack is installed. Rushing this part can lead to uneven pressure and wasted sheets.
For new installations or press startup help, our team can advise on how to build the pack correctly for the press type and the job. If a machine has had a blanket change, new plates, or a recent service, the packing should be confirmed again before production starts. A small error at this stage can show up later as patchy solids, image wear or constant adjustment during the run.
There is no electrical or gas connection needed, only correct handling and storage. Keep sheets flat, dry, and away from heat sources, oil, and chemical splash. That basic care keeps the material useful and stops warping or marking before use.
Care, handling and servicing over time
Good packing material should stay consistent from the first sheet to the last. Store packs in a dry room, flat on a pallet or shelf, and avoid leaving them in the back of a vehicle in the sun. In Gauteng, dust and temperature swings can affect storage conditions, while summer humidity can soften lesser material and make handling less precise.
During use, keep the sheets free from grease, blanket wash residue, damp patches, and offcuts. If a sheet is creased or crushed, do not put it back into critical packing work. It is better to replace it than to build an uneven press condition that causes trouble all day. A clean packing stockroom also helps your operators identify the correct thickness faster, which saves time on busy shifts.
If your machine starts to show recurring pressure issues, our technical support team can help with blanket assessment, plate handling training, and production troubleshooting. Sometimes the issue is not the plate or blanket itself, but the packing underneath it.
Working out packing thickness
Before ordering underpacking sheets, confirm the press type, the area of use, and the thickness range you need. You should also know whether you need full sheets, cut pieces, or a mixed pack for different machines. On the supply side, it helps to state the quantity per month, the preferred delivery town, and whether the order is for one site or multiple branches across South Africa.
- Press make and cylinder size
- Required thickness range in microns or millimetres
- Sheet size or cut format needed
- Application: plate, blanket, or finishing
- Storage conditions in the plant
- Delivery area and frequency
If you are balancing supply across Industria West, Roodepoort, Randburg, Midrand, Germiston or Pretoria, our logistics team can help plan stock so you do not run short mid job. Send your enquiry through our contact form and include your machine details, current packing setup and the kind of work you run most often. That way we can match the product to the press instead of guessing.
Key facts
| Product type | Underpacking sheets for blanket and plate cylinder setup |
|---|---|
| Use | Thickness correction and pressure control in press make-ready |
| Common sizes | Cut sheets, full sheets, and job-specific packs |
| Thickness control | Dependable, measured packing for repeatable setup |
| Site needs | None, manual installation only |
| Supply area | Nationwide from Johannesburg City West |
