Filler gone hard in the tub after the lid came off

You open last year’s tub and the knife bounces. Filler gone hard in the tub is ready-mixed paste that has already done what it does on the wall: it has lost water and set. The lid was off, it never sealed, or the parcel arrived that way. Ready-mixed filler hardens as water leaves it. Powder you mix on the day is a different product, and it is not among the eight pastes in this comparison.

Products Compared used the amazon.co.uk cards from 15 October 2026, section 9 of the Consumer Rights Act 2015, and Toupret’s note that ready-to-use filler has a storage life worth protecting. We will not invent an opened life in months, or a recipe of water to stir back in. Links to amazon.co.uk use the tag pcuk26-21. A qualifying purchase can earn a commission at no extra cost to you. Pack size is on the surface filler buying guide.

In short

Keep the lid on. Ready-mixed paste lumps when water leaves it, which is what an unsealed tub allows. Do not thin a hard tub back to a spreadable paste. If the pail arrives open or already hard, that is a satisfactory-quality problem under the Consumer Rights Act 2015, section 9. Buy a size you will finish. A 5 kg pail is the expensive version of a lost lid.

Ready-mixed filler hardens when water leaves it

On the wall, drying is the cure. In the tub, the same drying is spoilage. The paste is usable while it still holds water. Leave the surface open to the room and that water goes into the air. The top skins, then the body goes lumpy, then the tub is a block. It has not become a product you can grate back into a hole.

All eight listings in the surface filler comparison are ready-mixed pastes. Palace, Polycell, Sinto, FOME FLEX, Decex’s Polycell tube, and the Zawan kit share that weakness. None of them is a bag of powder you can leave dry until the next hole. Toupret, comparing powder with ready-to-use filler, treats getting more life out of the ready-mixed product as a real limit. The heading supports the topic. It does not give a number of months we are willing to print.

Hard filler in the tub is not full cure on the wall. Cure on the wall is the layer you meant to harden, inside the depth the sheet allows, at a temperature such as the 20°C on Palace’s 1 kg sheet. A solid tub is paste you can no longer place. Throw the spent paste away with the tub, and keep the dust out of the room you are about to decorate.

The lid is the storage method

Press the lid on until it seats. A film smoothed onto the paste before the lid is only as good as the seal you actually made. A cling-film and water revival sits outside the sources. A lid left off means the next session is lumpy. Put the lid on before you wash the knife. A knife left across the rim leaves the lid proud and the seal fails.

Store the tub where you will not knock the lid, and where it will not bake on a radiator or freeze in a shed if the label says to avoid that. Sinto’s 5 kg card lists a lid among the included items. That lid is the storage method for the most expensive paste in the set, £16.33 on 15 October 2026. A 600 g tub fails the same way and wastes less money.

The two-pack, B0G51LQMSN, at £2.50, is two 600 g ready-mixed units. Leave the second sealed until the first is finished or spoiled. Two lids are two chances to get storage wrong, not a longer life. Check the seal when the parcel arrives. A loose lid in the box is easier to return than a tub you discover is hard on decorating day.

A skin on top is not a licence to thin the tub

A skin on a filled crack is a drying stage: it can look ready while the middle is soft. A skin on the paste in the tub means the surface has already started to dry in storage. Do not peel it and stir the rest, and do not add water. Neither method was in the datasheets we checked.

If only the top has skinned and the paste underneath still spreads, you are guessing. When the repair matters, use a small new tub. Stop if the paste is lumpy. Lumpy filler in a hairline leaves nibs you then sand. The £1.25 Palace fine tub is cheaper than that afternoon.

Do not confuse a skinned tub with a product that states a 30-minute skin on the wall. Palace’s 1 kg sheet uses about 30 minutes for the skin of a placed layer at the start of drying. That clock starts when you have filled the hole. It does not describe a tub that sat open overnight. Leave the overnight tub closed next time. Replace it if it has gone solid.

A pail that arrives open or already hard

A parcel that arrives with the lid off, the tub split, or the paste already hard is not a storage mistake you made. Section 9 of the Consumer Rights Act 2015 is the satisfactory-quality rule for that delivery. Photograph the lid and the paste before you try to use them. Use the return route on the amazon.co.uk order. Filling a wall with it, then complaining, is a weaker record than a photo of the unopened failure.

Sinto’s 5 kg pail at £16.33 is the costly version. The included-items line names a lid. If that lid is missing or the paste is a brick, the loss is the whole pail. Palace fine at £1.25 is a smaller loss. A low price is not a reason to accept a split tub.

Zawan at £21.00 had no review line. A kit that arrives short of its tools, or with a hard paste, is the same section 9 point without a star rating to argue from. Keep the listing. The wall filler cost guide has the eight shelf prices so you can see what you are asking to replace. We are not a returns desk. The hard delivery is a quality problem, not a puzzle to rehydrate.

Buy a size you will finish

A few picture holes want a small ready-mixed tub or a tube. Palace fine, 600 g, at £1.25, and Polycell’s 330 g tube at £3.49, are the entry sizes in this set. A room of cracks can justify Palace’s 1 kg at £6.99, which you are more likely to finish while the lid still matters. A 5 kg pail for someday is how someday becomes a solid block in a cupboard.

Match the paste to the hole as well as to the month. Fine filler in layers of no more than 3 mm will not become a deep-hole product because you bought a lot of it. Multi-purpose paste at about 10 mm will not become flexible sealant because the tub is large. Storage does not fix a wrong type. Buy in a pack the next two weekends will actually open.

Powder, if you later need it for a deep hole, is mixed when you use it. That is its storage advantage, and it is outside these eight ASINs. Until then, the paste you have is a sealed tub, a seated lid, and a size that does not outlive the work. If the tub is already hard, replace it or return it. Do not take it to the wall.