Polishing an old cement tile floor means wet-grinding a few tenths of a millimetre off the wear layer with diamond abrasives of progressively finer grit, until the wear evens out and the pattern recovers its colour. It is irreversible: that pigmented layer is usually between 3 and 5 mm thick and does not grow back. Before you start, you have to check how much of it is left.
This guide is about the recovery work itself: what to look at before switching the machine on, when it is better not to polish, which grits are used and what treatment comes afterwards. Identifying and dating antique cement tiles, and the day-to-day cleaning routine, are separate subjects.
Polishing, buffing or crystallising? They are not the same thing
Of the treatments offered for a cement tile floor, only two actually remove material from the tile. Confusing them is behind most ruined floors: someone asks for “a bit of a buff” and a contractor turns up with crystalliser and steel wool.
| Treatment | What it does | Does it remove material? | Is it reversible? | Suitable for cement tile? |
|---|---|---|---|---|
| Maintenance cleaning | Lifts surface dirt with a pH-neutral soap | No | Yes | Yes, this is the routine |
| Stripping | Removes old waxes, oils and sealers | Only the added coatings | Yes | Yes, essential before polishing |
| Polishing or diamond grinding | Cuts the surface back with wet diamond abrasives | Yes, tenths of a millimetre | No | Yes, if enough wear layer is left |
| Buffing with wax or resin | Adds a film of gloss and protection | No | Yes, it can be stripped off | Yes, but it closes the pores and has to be renewed |
| Crystallisation | Acid attack with steel wool to create a mirror finish | Yes, and it burns the pigment | No | No: the wear layer is cement, not marble |
Crystallisation was developed for marble and for terrazzo with marble aggregate: an acid reacts with the calcium carbonate in the stone and, with the heat generated by the steel wool, forms a hard, glossy film. The wear layer of a cement tile is pigmented cement, and cement does not crystallise: it is simply attacked. What is left behind is whitish clouding, uneven gloss and burnt colours.
How much can be polished off? The wear layer sets the limit
All the polishing a tile will take in its lifetime has to fit within the 3 to 5 mm that the wear layer usually measures. Below it there is grey mortar: the moment it shows through, the pattern is gone for good at that spot.
A cement tile is pressed in three layers and is not fired, it cures. On top, the wear layer: cement, fine mineral filler and pigment; underneath, a fine mortar and a coarse mortar base that provides the thickness. In historic tiles the total is usually over 2 cm; in the formats we produce today it ranges from 1.5 to 1.8 cm, with the 20 × 20 cm square —1.30 kg and 25 tiles per square metre— as the most common reference.
How to measure the wear layer before deciding anything
No instruments are needed. Look for the edge of a loose tile, or the gap left by a missing one in a corner: the coloured band stands out from the grey of the base with the naked eye. If less than 2 mm of colour is left, the floor will not take a polish that involves coarse grinding.
The second check is the one almost nobody makes: polishing levels downwards. An old floor is worn selectively —heavily down the middle of the hallway, hardly at all in the corners— and the machine does not fill anything in: it cuts the whole floor down to the level of the most worn area. If the middle of the hallway is at its limit, that limit applies to the entire room.
When should an old cement tile floor not be polished?
There are five situations in which polishing makes the floor worse instead of recovering it. It is worth ruling them out before asking for a quote.
- The wear layer is spent. If the pattern has faded in the traffic areas and a uniform grey is showing through, there is no colour left to bring back: polishing simply finishes it off.
- There are loose or hollow tiles. A tile that sounds hollow when you tap it has lost its bond and the machine will lift it or break it: the tiles are relaid first, and polished afterwards.
- There is rising damp or active efflorescence. White powder that keeps coming back after every clean means salts on the move; polishing adds more water and the sealer traps the problem underneath.
- There is lippage caused by movement in the substrate. Steps of more than one or two millimetres cannot be ground out without eating the wear layer of the high tiles: those are lifted and relaid.
- It is not a cement tile. Nolla mosaic, old stoneware and terracotta are fired ceramic pieces with a vitrified or glazed surface: they do not respond to the polishing of a cement floor.
There is a sixth reason, backed by regulation: in wet areas, the more gloss, the less slip resistance. Spain’s Technical Building Code (CTE) sets out in its DB-SUA 1 section the class required for each use, measured with the pendulum test of the Spanish standard UNE 41901:2017 EX: class 3, with Rd values above 45, is what is required for outdoor areas, swimming pools and showers.
It is worth not mixing products up when quoting figures: the pendulum value we have published is the one for our 20 × 20 cm hydraulic terrazzo —59.5 PTV wet, class 3, laboratory test report no. 4718—, and the cement tile was tested separately, in report no. 9102. That value, moreover, is the one for a tile fresh out of the workshop: after polishing to a gloss finish, the Rd has to be checked on the finished floor. In bathrooms, showers and courtyards, a satin finish is the safe option.
| What you see | What it means | What to do |
|---|---|---|
| Faded pattern and uniform grey down the middle of the traffic route | Wear layer spent in that area | Do not polish: replace those tiles or accept the patina |
| Hollow sound when tapped with your knuckles | Loss of bond with the substrate | Lift and relay before any abrasive touches the floor |
| White powder that returns after every clean | Efflorescence caused by rising damp | Solve the damp first; sealing over it traps it in |
| Circular scratches or patches of uneven gloss | Someone has been over it with an angle grinder, a floor sander or a crystalliser | Real coarse grinding is needed; wear layer thickness is lost |
| Lippage of more than 1–2 mm between adjoining tiles | Movement in the slab or in the bedding layer | Lift and relay; it cannot be corrected by polishing |
How is an old cement tile floor polished, step by step?
There are six stages, and the polishing itself is the fourth. Skipping the first three turns a restoration into a wrecking job.
- Assessment and test areas. Measure the wear layer at the edge, mark hollow or cracked tiles with tape, check for damp and photograph the pattern in case tiles have to be replaced.
- Replacement and relaying. Replace broken tiles and re-bed loose ones before polishing, so that the final pass levels the new ones in as well.
- Cleaning and stripping. Remove waxes, oils, old sealers and cement residue with a low-aggression stripper. No muriatic acid, vinegar, bleach or acid cement removers: acid dissolves the cement in the wear layer.
- Coarse grinding, only if it is needed. 50–60 grit wet diamond, with a low-speed single-disc machine, water feed and slurry extraction. This is the stage that eats material and the first candidate to be dropped.
- Honing. A 120 → 220 → 400 sequence, each grit at least twice and in crossed passes, until no marks are left from the previous one. The perimeter and the corners are finished by hand with diamond hand pads.
- Grouting, drying and sealing. If the work has opened up the joints, they are grouted before any treatment: choosing the right grout for a cement tile floor matters as much as the polishing. Then 24 to 48 hours of drying and the water repellent.
| Diamond grit | Stage | What it is for | When to skip it |
|---|---|---|---|
| 50–60 | Coarse grinding | Level out lippage and lift ingrained rings and cement residue | Almost always on an old floor: this is the one that eats the pattern |
| 120 | First honing pass | Erase the marks left by the coarse grind and bring out the colour | Rarely: it is usually the starting point |
| 220 | Honing | Even out the tone across the whole floor | Not advisable |
| 400 | Matt satin finish | Close the pores, smooth and uniform to the touch | No: it is the finish that suits an old floor best |
| 800 or finer | Gloss | Increase reflectivity | Yes, in bathrooms, showers and courtyards |
Can I polish the cement tile floor in my own house?
The assessment, the deep clean and the stripping are jobs a homeowner can do. Diamond polishing is not, unless you already handle a single-disc machine every day.
The reason is not the price of the machine, which can be hired: it is that it does not forgive. A disc left standing for two seconds leaves a hollow for ever, and the wrong grit takes the pattern with it. Three tools ruin these floors over and over again: the floor sander, which spins too fast and leaves waves; the angle grinder, with which it is impossible to hold a flat plane; and the high-speed marble polisher.
It is worth saying plainly: at Demosaica we make and reproduce cement tiles in our workshop in Seville, but in situ polishing is carried out by companies that specialise in floor surfaces. What we do handle —and it is usually the missing piece in this kind of job— is remaking the tiles that no longer exist.
What do you do about broken or missing tiles?
They are replaced before polishing, never afterwards. A new tile on an already polished floor stands out in tone and in gloss; laid beforehand, it goes through the same sequence of grits as the rest and blends in.
There are three sources: spare tiles from the original job —they turn up in storerooms and cupboards more often than you would think—, the reclamation market and made-to-measure reproduction. For the last one, a single original tile or a few to-scale photographs are enough: the pattern mould is remade, the colours are matched against the colour chart and the missing tiles are pressed, exactly as with any custom cement tile.
Watch the format. Historic floors are usually 20 × 20 cm squares, but there are also hexagons, octagons and unusual layouts, such as the Chakar, 20 × 17 cm, in our catalogue. If the size does not match to the millimetre, the joint gives it away: measure several tiles before ordering.
What treatment does a newly polished cement tile floor need?
A water-repellent, or water- and oil-repellent, sealer applied while the pores are open, between 24 and 48 hours after finishing. Never wax before sealing: it traps the dirt underneath.
Those one or two days are the most delicate moment of the whole job: the pores are open and any drop of oil, coffee or wine goes straight in. To give an order of magnitude, our 20 × 20 cm hydraulic terrazzo —also a concrete tile— absorbs between 5.9 and 6.2 % (UNE-EN 13748-1, the Spanish version of EN 13748-1), against 0.5 % for a porcelain stoneware tile. Cover the traffic route with cardboard and do not move furniture back until the floor has been treated.
From then on, maintenance is the ordinary kind: pH-neutral soap, no acids and the water-drop test to know when the treatment needs renewing. Two things you should not do to a newly polished floor: crystallise it, and apply linseed oil, which stays tacky and traps dust.
Frequently asked questions about polishing an old cement tile floor
How many times can a cement tile floor be polished?
It depends on how much wear layer is left, not on how old the floor is. With the original 3 to 5 mm, a floor that has never been polished will normally take one intervention with coarse grinding and, later on, a light refresh. If it has already been polished once, measure the edge: below 2 mm of colour, any aggressive abrasive will take the pattern with it.
Can a cement tile floor be polished without lifting it?
Yes, and that is the usual way to do it. Polishing is carried out in situ with a single-disc machine, water and extraction, without touching the laid floor. Lifting only makes sense when there are hollow tiles, damp in the substrate or level differences caused by movement, and always accepting that some of the tiles will break as they come up.
How much does it cost to polish an old cement tile floor?
There is no useful benchmark price, because every floor starts from a different condition. What moves the figure is the number of stages: whether coarse grinding is needed, how many tiles are replaced, whether regrouting is required and which final treatment is applied. Ask for a quote based on a test area on the actual floor, not per square metre sight unseen.
Can cement tiles be polished with a floor sander or an angle grinder?
No. A floor sander spins too fast and leaves waves and circular scratches that cannot be corrected without losing millimetres of wear layer. With an angle grinder there is no way to keep the plane flat and every point of contact leaves a mark. A cement tile floor is polished wet, with a low-speed single-disc machine and diamond abrasives.
What happens if I clean an old cement tile floor with muriatic acid or an acid cement remover?
You damage it permanently. A cement tile is pressed cement that has never been fired, not ceramic: the acid dissolves the binder in the wear layer, leaves the surface sandy, dulls the colours and opens the pores. A floor attacked with acid can only be recovered by polishing, that is, by spending part of the thickness it had left.
Can a cement tile floor laid over underfloor heating be polished?
Yes, polishing does not affect the installation, but switch the circuit off and let it cool down completely before starting: polishing wet over a warm floor, the water evaporates before it can carry the slurry away. If the job involves lifting tiles, check the usual mistakes made when combining cement tiles and underfloor heating first.
Before you hire anyone to polish the floor, spend ten minutes on the basics: tap the tiles with your knuckles, find the edge of a loose one and measure how much colour is left. With that one figure, the conversation with the contractor changes completely. And if there are gaps, send us photographs and the dimensions of the floor and we will look at reproducing the missing tiles.
