Fine grounds are stuck in the mesh of my press filter and nothing dissolves them

Preventing it is easier than curing it, and it comes down to two things.

Grind coarser. A press should be at the coarse end, and fines are what work into the mesh. If your grinder produces a lot of fines — common with entry-level or worn burrs — you will clog filters no matter how you clean them.

Rinse immediately after use, before anything dries. Wet grounds rinse out; grounds that have dried into the mesh with oil around them are what you are dealing with now.

The habit that makes the biggest difference is discarding the grounds and rinsing the mesh straight away rather than leaving the pot until later. Ninety seconds, and the filter never reaches this state.

You are approaching it wrongly, and the reason is a category error worth spelling out: coffee grounds are cellulose and they do not dissolve in anything you would put in a kitchen.

The cleaning products people recommend for coffee equipment target oils and soluble residues — the brown film and the rancid taste. Vinegar attacks mineral scale. Neither is a solvent for plant fibre.

So no soak will remove them, however long you leave it. What you need is mechanical.

The effective approach is to take the filter assembly apart. Press filters unscrew from the plunger rod into separate discs — usually a mesh, a cross plate, a spiral spring and a base. Once separated you have access to both faces of the mesh with nothing behind it, and a brush or a rinse from the clean side pushes the particles straight out.

Most people have never taken theirs apart and are trying to clean a sandwich from the outside.

Once it is apart, what actually works:

• Rinse from the reverse side. Particles went in one way; push them back out the way they came rather than trying to force them through.
• A soft toothbrush on the mesh, wet, with the disc held against a flat surface.
• A short soak in a proper coffee equipment cleaner first, to release the oils gluing the particles in place. That is where those products genuinely help — not dissolving the grounds, but letting go of them.
• An ultrasonic cleaner if you happen to have one for jewellery or parts. This does work well and is wildly disproportionate for the problem.

Avoid anything abrasive on the mesh. It is fine wire and once it is distorted the filter lets grounds through forever.

One thing worth checking while it is apart: whether the mesh is still flat and the spiral plate still springy.

A press filter that has been forced or scrubbed hard often ends up slightly domed, and then it never seals against the wall of the beaker again. That produces grounds in the cup regardless of how clean it is, and people blame the grind.

Replacement filter assemblies are cheap and are sold for most models. If yours is distorted, that is a better use of an afternoon than cleaning it.