Paint sludge filter bag in 30 g/m² nonwoven

The 30 g/m² paint sludge filter bag: twice the basis weight, half the openness

Like Color Drain, this filter bag is made from thermally bonded polypropylene spunbond nonwoven with a hydrophilic finish. It weighs 30 grams per square metre instead of 15 and is noticeably thicker at 0.25 millimetres. Air permeability is 4,300 l/m²/s, roughly half the Color Drain figure. Tensile strength is documented at 50 N per 5 cm in both machine and cross direction, at elongations of 30 and 40 per cent respectively.

Those are the two reasons operations move to this bag: it takes more punishment, and it lets less through.

The usual trigger for the switch is a torn filter bag

With paint sludge, filter bag and filter sack mean the same component: the textile insert that sits in the holder and carries the solids. In practice, paint shops rarely change to the heavier nonwoven for theoretical reasons. The trigger is concrete. The bag tears as it is lifted out because the sludge is heavier than expected. Or it fails to take the load during filling, when the mixture arrives from the pipe with some force. Or there are more fines in the filtrate tank than the operation is comfortable with.

The 30 g/m² nonwoven answers all three. The documented 50 N per 5 cm gives the bag reserve for handling, and the denser structure holds back finer fractions better than the very open nonwoven does.

What tensile strength and air permeability mean in practice

The 50 N per 5 cm describes material strength in a tensile test on a narrow strip. It is a comparison value, not a statement about what the filled bag will carry, because the holder, the seam pattern and the load distribution all play their part. Where you notice the difference against the very light nonwoven is the moment the filled bag is moved.

Air permeability of 4,300 l/m²/s places the openness of the material. It sits at about half the Color Drain value and confirms the denser build. It cannot be transferred to water: with paint sludge, flocculation decides the clarity of the filtrate more than the structure of the nonwoven does. A well flocculated sludge gives clear filtrate through an open nonwoven, and a poorly flocculated one gives cloudy filtrate through a dense one.

Technical data, nonwoven filter bag 30 g/m²

Which paint sludge filter bags suit your process?

Both versions come in packs of 25 and fit the same holder. Comparing them in running production therefore costs no more than the time for a bag change.

Questions we are asked about the nonwoven bag for paint sludge

With the heavier nonwoven, most queries are about the interaction with the upstream process and about fit in existing equipment.

Does the 30 g/m² nonwoven make up for poor flocculation?

No. Where fines come from inadequate flocculation, a denser nonwoven only moves the problem: the bag blinds off faster and the water stands. The bag is a filter medium, not a substitute for the chemistry upstream.

Will the bag fit coagulation systems from other manufacturers?

Often yes, because the holders are similar. It is only binding once the internal dimensions have been compared. Tell us the type of system and the box dimensions and we will check it.

Can the bag be used for other sludges?

For light, watery sludges in a suitable holder, yes. For mineral or abrasive sludges the 200 g/m² geotextile bags are the right product group, both for material strength and for working load.

What does 50 N/5 cm mean?

It is the maximum tensile force on a 5 centimetre wide strip of material in a tensile test. It is a comparison value for material strength, not a statement about the carrying capacity of the filled bag. What the bag actually carries depends on the holder, the seam pattern and how the load is distributed.

Is the nonwoven bag suitable for water-based paint sludge?

Yes, provided the sludge is flocculated and contains no solvents that attack polypropylene. The same selection criteria apply as for solvent-based paint sludge: floc stability and mechanical load decide, not the colour of the material.

How do I dispose of the filled bag?

Bag and paint sludge are disposed of together, according to the waste classification of your sludge. That classification is made by your waste contractor and depends on the paints and additives you use.