We weave, cut and finish filter press cloths in Werther in Westphalia. Five fabric grades cover direct cake filtration and precoat filtration, each in six standard plate sizes from 400 to 1000, and everything outside that is made to drawing or to sample.
PP filter cloth · nominal 10, 20 and 25 µm · 46 µm pore size for 67L · standard formats and custom manufacture
| Grade | Documented construction | Role in the process |
|---|---|---|
| 3L | 10 micron nominal; multifilament and staple fibre; 620 ± 40 g/m²; 0.95 mm; 3 ± 1 l·dm⁻²·min⁻¹ | densest direct grade |
| 6L | 20 micron nominal; monofilament warp, multifilament weft; 400 g/m²; 670 µm; 6 l·dm⁻²·min⁻¹ at 200 Pa; to 90 °C | fine intermediate step |
| 7L | 25 micron nominal; multifilament; no further values documented | economical standard grade |
| 15L | 25 micron nominal; monofilament and multifilament; 320 ± 40 g/m²; 0.5 mm; 15 ± 6 l·dm⁻²·min⁻¹ | more permeable alternative |
| 67L | 46 micron pore size; monofilament; 275 g/m²; 380 µm; 111 l(n)·m⁻²·s⁻¹ at 2 mbar | support fabric for precoat filtration |
Air permeability for the 3L and the 15L is documented without a test pressure. Those two figures should not be set against the 6L and 67L values without that reservation.
It is tempting to read the column of numbers as a scale and to pick a place on it. The datasheets say something else.
Between the 3L and the 15L the nominal rating changes by a factor of 2.5, from 10 to 25 micron. Over the same step the fabric weight falls from 620 to 320 g/m², so close to half. The thickness halves from 0.95 to 0.5 mm. And the air permeability rises from 3 to 15, five times over. Compare two cloths by their micron figure and you are comparing the one number that differs least.
The second point is more surprising. The 6L carries 120 warp and 28 weft threads per centimetre, more than double the 60 and 12 of the 3L. It is still listed at 20 micron against the 3L at 10. The reason is the yarn: the 3L reaches its fineness through multifilament and staple fibre, whose filaments fill the spaces between threads, while the 6L reaches its structure through a close grid of fine monofilaments. Two construction principles that behave differently in service, and the micron figure shows neither of them.
This decision comes before the fabric choice, because it is about the process.
In direct cake filtration the fabric holds the solids back first. Within a short time a filter cake forms from the process medium itself and takes over a growing share of the separation. That is why filtrate at the start of a cycle often looks different from filtrate later on. A direct cake filtration cloth is what the 3L, 6L, 7L and 15L are.
In precoat filtration a filter aid is built into a layer on the fabric before or during the process. That layer does the fine filtration, and the fabric carries it while getting in the way as little as possible. The 67L is the grade for that.
Treating the 67L as a fifth, coarsest fineness step is the most common selection error in this product group. Without a precoat layer it works like a very open fabric.
A chamber filter press is a batch machine, and the cloth mostly sees aqueous suspensions: process water carrying solids, rinse and wash waters, mineral sludges, residues from metalworking and surface treatment.
A filter press cloth for sludge dewatering is chosen less by how fine it is than by how the solid behaves. With an evenly distributed, well flocculating sludge a load-bearing cake forms quickly and does the separation work, so an industrial sludge filter press cloth mainly has to hold that cake and let liquid through. With a high fine fraction or a strongly compressible cake the fabric matters much more, and a denser grade is usually the direction to go.
A slurry filter press cloth for an abrasive mineral suspension has a third requirement again: mechanical stability at the edges and seams, because that is where wear starts.
A 25 micron filter cloth appears twice in this range, and the pair gets mixed up more often than any other.
| 7L | 15L | |
|---|---|---|
| Nominal rating | 25 micron | 25 micron |
| Yarn construction | Multifilament | Monofilament and multifilament |
| Weave | not documented | Plain |
| Fabric weight | not documented | 320 ± 40 g/m² |
| Air permeability | not documented | 15 ± 6 l·dm⁻²·min⁻¹ |
| Role | economical standard | more open, for throughput and cake release |
If your process runs and the filtrate is right, the 7L is the sensible replacement. If the press is the bottleneck or the cake stays on the cloth, the 15L is the grade to test.
All five grades are polypropylene. A polypropylene filter press cloth is dimensionally stable, does not absorb water and stands up to many aqueous and industrial media, and that covers a large part of what runs through a chamber filter press. The market shortens the term to PP filter cloth, and a polypropylene filter cloth offered elsewhere will usually mean the same material.
It does not cover everything. Concentration, temperature, pH and any solvents present decide the case together, and we do not give blanket resistance assurances. Only one grade in this range carries a documented temperature limit, the 6L at 90 °C, and we do not transfer that figure to the others.
Standard sizes run from the 400 plate to the 1000 plate: 400, 470, 500, 630, 800 and 1000.
One detail causes more return questions than any other. The plate size is not the finished size of the cloth. A cloth for a 630 plate is larger than 630 millimetres, because the overhang, the edge and the inlet area are added to it. So when you order a replacement filter press cloth, give us the plate size rather than the measured cloth size, or send us the old cloth.
Standard sizes are ordered straight from the product pages above. For anything else we quote.
You can buy a filter press cloth here in six standard plate sizes. Beyond those, the job is rarely a catalogue transaction. Even inside a single plate pack the head, end and chamber plates often differ, and a filter press cloth supplier who only ships stock sizes runs out of answers at that point.
As filter press cloth manufacturers go we are on the small side, and that shows in the batch sizes we take on: single cloths and repeat orders of a handful are normal here. WINKLER makes and converts filter press fabric in its own plant. We select the fabric grade, the edge finish, the inlet and the fixing method against the press, and we make small quantities. That is why the first step in a special enquiry is not a part number but a drawing, a sample or a photograph.
Head, end and barrel neck cloths are made from all five grades. Special contours and cut-outs run through our laser system.
We ship from Werther in Germany. Filter press cloths go to the UK and Ireland regularly, and a replacement filter press cloth for a UK plant is quoted the same way as one for a German plant. The same holds for the rest of Europe. Filter press cloths for Europe leave on the same routes, and a filter press cloth for the Netherlands, Sweden, Denmark, Norway or Finland is built from the same standard sizes and the same conversion options. Prices for the standard sizes are shown on each product page; for special sizes we quote against your details.
Two things come up in enquiries often enough to state here.
We do not supply filter aid. Diatomaceous earth, cellulose and perlite products belong to the precoat process, not to the cloth, and they come through your existing suppliers.
We do not supply cloth washing equipment. Spray bars, washing pumps and automatic cleaning units are not part of our range and we do not assess them. What we can say concerns the fabric, and that is in the cleaning guide.
Start from the goal rather than from the micron figure. Cloudy filtrate points to a denser grade, a slow press to a more open one, a sticky cake to the calendered face of the 15L. The selection guide walks through it.
No. Nominal ratings are range classifications. Only the 67L carries a measured pore size, and that is a different type of figure again.
Yes, from all five fabric grades. Those are converted parts rather than stock items, so they are quoted individually.
Only the 7L carries a conformity and migration document under EU 10/2011, and that document has to be checked against your own requirement. We do not derive food or pharmaceutical suitability from the material alone.
Standard sizes are priced on the product pages. A filter press cloth price follows the plate size above all: the 400 plate is the entry point and the 1000 plate the top of the standard range. Converted parts, head and end cloths and special contours are quoted against your details.
Give us the plate size rather than the cloth size, plus the position in the plate pack, the inlet geometry, the edge finish and the fixing method. A cleaned old cloth answers all of it at once.
There is no general figure. Medium, solid, pressing pressure, number of cycles, cleaning method and temperature all decide it. Your own change history is the most useful basis.
Selection guidance and technical background for the products in this category.
Nominal micron rating, measured pore size and air permeability are three different things ➔ what each one says and what it does not. Read the...
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Monofilament, multifilament or hybrid ➔ pick a filter press cloth from filtrate quality, throughput and cake release, not from micron. Read the guide!
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How to clean filter press cloths without damaging them, why a cloth blinds and how to tell that washing will not help any more. Read...
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