Granite Sealer Price per Square Meter: Which Square Is Being Priced?
A granite sealer price per square meter only means something once you know which square is priced. On a 600×600×30 mm slab the visible face is 0.36 m², while all six faces come to 0.792 m² — 2.2 times as much. Fix the basis before you compare two quotes.
What does granite sealer price per square meter actually quote, and why split the question first?
A granite sealer price per square meter only makes sense once it is split in two: you measure the paved area, the factory calculates the developed area of six faces. Take a 600×600×30 mm slab. The visible face is 0.36 m²; the six faces come to 2×0.36 + 4×0.6×0.03 = 0.792 m², exactly 2.2 times as much. On the same batch, sealer and labour are costed against 2.2 times the area, so the two quotations cannot line up. So the first question is not the price, it is "which square does your rate use?". Until that is fixed, two quotes can differ by a factor of two and both be honest, because you are comparing methods rather than prices.
Which six faces are they, and which one drinks the most sealer?
The six faces are the visible face, the back and four edges. The back takes the most: it is a sawn face with no polishing, so every capillary is open. The four edges come next, also cut surfaces, and their area grows with thickness, so thick slabs climb quickly. The visible face is polished and the tightest, so it absorbs the least. Sealer is therefore not spread evenly over six faces; the back and the edges carry most of the consumption. Nor is the ratio fixed at 2: the smaller the slab and the thicker it is, the larger the share taken by edges and back, and the higher the multiplier. On 1,000 m² of paving, 600×600 bills out at 2,200 m² of developed area and 300×600 at 2,300 m²; the 100 m² gap is not an arithmetic error, it comes from the slab size. The numbers below can be checked with 2×L×W + 2×L×T + 2×W×T. The 1000×600×50 row is an arithmetic example only: our polished slabs are stocked at 30 mm, and G603 comes in that one thickness.
| Slab size | Visible face, m² | Six faces, m² | Ratio |
|---|---|---|---|
| 600×600×30 | 0.36 | 0.792 | 2.2 |
| 300×600×30 | 0.18 | 0.414 | 2.3 |
| 1000×600×50 | 0.6 | 1.36 | 2.27 |
Does every slab need six-side sealing?
No. The test is whether the back meets water. With wet fixing, where the slab is bedded on cement mortar or adhesive against floor or wall, the back sits against an alkaline mix and moisture travels up through it, so six-side sealing applies; on light-coloured stone it shows first, because efflorescence and damp patches start on the untreated face. With dry fixing the slab hangs over a cavity and never touches mortar, but seepage still enters that cavity, so whether the back is sealed is settled by the facade detail and the project specification, not left clear by default. The one place that is masked off is the anchor pocket, because sealer inside the groove weakens the structural adhesive bond, and that follows the detail drawing. One order often contains both methods, so mark them separately on the cutting list instead of letting the workshop apply one rule to everything. Why absorption matters this much is covered in our article on frost and freeze-thaw.
Three pricing bases turn up on quotations — how do you force them into one?
The table below sets out which way each basis pushes the total; read it before writing the enquiry. The move is to pin down three lines: which area the rate is based on, how many coats with how long between them, and whether labour and site work are included. Leave those lines out and the supplier will pick the cheapest basis available to them, and you end up comparing three different numbers. The coat line is the easiest to fudge: "two coats" with no interval stated between them says nothing. Two quotes can still be compared, but first check both cover the same faces. If both seal six faces and one is merely priced on visible area, convert in one step: developed-area rate x multiplier = the rate restated on the visible face, and visible-face rate / multiplier = the developed-area rate, with the multiplier from the last column of the table above. Where a quote covers the face only, build its area up to six faces with the multiplier before applying the rate, and never divide a single-face rate by the multiplier.
| Pricing basis | Which way the total moves | What to write on the enquiry |
|---|---|---|
| Visible-face area | Lowest total (usually one face only, back and edges extra); where the rate is per visible m² but covers six faces, the total matches the developed basis while the restated rate is the higher of the two | State how many faces the rate covers; if one, ask for the rest itemised |
| Six developed faces | Largest figure, but it matches real consumption | State that it is costed as 2×L×W + 2×L×T + 2×W×T |
| Material volume (litres/kg) | Closest to cost, but you must convert back to area | State that it is converted using the batch data sheet coverage in m²/L |
Should sealing be done at the factory or on site?
The test is whether the slab will be cut again after delivery. Factory work joins onto polishing and packing: one less unpacking, one less storage and second handling, and the slab goes straight onto the crate. The price is that transport knocks and site cutting open the film, and a freshly cut edge is raw stone, as good as untreated. Site work lets the supervisor watch the process, but yard, weather and rework are yours: rain, damp faces and strong wind all stop coating, and a squeezed programme means rework. The rule is single: if the slab will be cut, drilled or edge-polished on site, the cut edges must be re-coated, even when six-side sealing was done at the factory. Our stock Sesame White G603 polished slabs are 30 mm, 346 m² per 20 ft container, 100 m² minimum order, 5 days regular lead time, so sealing has to be scheduled before packing rather than raised the day before loading.
On arrival, how do you check the sealing was actually done?
Throw water on it. If it beads and runs off, the face is sealed; if it soaks in fast and the colour darkens, it was missed or never done. Do not stop at the face: wet the four edges, the underside, cut edges and the inside walls of holes, except where the detail drawing says to leave them clear. Then ask for two things, a sample of the same batch sealed and unsealed, and the data sheet for that batch of sealer, because coverage in m² per litre is written there and it is what tells you whether the quantity used matches the area. Run the water test after the curing time stated on the data sheet; test straight after coating and even a good job will absorb.