Technical · sealing super white dolomite
The science of sealing dolomite.
The specifier's version. What the coating is, why a carbonate stone has no covalent partner for silicon, how it anchors anyway, where dolomite genuinely differs from the quartzite it gets mistaken for, and where the honest limit sits. It is the one and only next-generation sol-gel surface coating in Australia, and it earns that by being straight about the chemistry.
The coating, in short
What we put on the stone.
The mineralogy that matters
Dolomite is not quartzite.
The single most useful thing a specifier can settle before sealing a super white slab is which stone it actually is, because the two are constantly confused and they behave in opposite ways to acid. It comes down to what the stone is made of.
Dolomite, the carbonate
- ·A calcium magnesium carbonate. Chemically a cousin of marble and limestone.
- ·Reacts with acid. Lemon, wine, vinegar and acidic cleaners dissolve the surface and etch it.
- ·Softer and more absorbent than a true quartzite, so it stains as well as etches.
- ·Has no surface silanol groups for the coating to bond to covalently.
Quartzite, the siliceous stone
- Silicon dioxide, a genuinely hard, metamorphosed sandstone.
- Broadly acid-resistant, so it does not etch the way dolomite does.
- Silanol-rich, so on real quartzite the coating forms a covalent Si-O-Si bond to the stone.
- The catch: much of what is sold as super white quartzite is actually dolomite, so verify before you assume acid resistance.
The practical test: a drop of a mild acid on an offcut will fizz on carbonate dolomite and do nothing on quartzite. It also etches the dolomite where you test it, so it is done on a hidden offcut, never on the installed top. We can usually call it at the quote.
The carbonate question
Carbonate has no silicon to bond to.
Here is the honest chemistry, stated plainly. Pure carbonate, the calcium magnesium carbonate that dolomite is made of, has no surface silanol groups, so there is no covalent Si-O-Si bond from the coating to the stone the way there is on granite, real quartzite, glass or concrete. We will not pretend otherwise. A covalent bond to every grain is not how a surface repellent anchors on a carbonate, and it is not what makes it work.
It anchors by three routes instead: mechanical interlock into the pore mouths and grain contacts, a self-condensed silica-like network with real Si-O-Si bonds inside the coating itself, and hydrogen bonding to the surface. That is the general carbonate mechanism, and it is set out in full for every calcium-based stone in stone and sealer chemistry. What follows is the part specific to dolomite.
Dolomite is the dense carbonate, so the finish is load-bearing
On open, porous limestone and travertine the porosity is the strength, and more of it means a better anchor. Dolomite sits at the other end of the same family: a dense, tight carbonate with far less open structure to key into. That flips the emphasis. Here the surface finish decides the anchor. A honed top offers more mechanical purchase than a tight, polished one, which is why we assess and prepare your actual slab before we seal it.
The point that gets missed: repellency is a surface-energy effect, and it is decoupled from any grain-to-grain bond. A silicon treatment still raises the water contact angle and cuts absorption on a carbonate even where it forms no covalent bond to the stone. So the wording stays honest and precise: it anchors into the mineral and pore structure, and we claim nothing more than that.
The real-world resistance
On a benchtop, oil is the mark that stays.
The protection lives at the surface, where the cooking, wiping and spills happen, and it meets the same four loads every sealed surface faces: cleaning and abrasion, chemical, UV and oil. Each has an honest bound, and the full account of how the coating handles all four, with the test methods behind them, is in the four real-world resistances. On a white dolomite top, two of them decide the day.
Oil, the benchtop problem
Oil lifts instead of soaking in
Cooking oil and grease are what mark a white dolomite top for good, and a plain water-repellent seal does nothing about them. Here oil sits on the surface and lifts in cleaning rather than absorbing. It is an outcome, not a number: not fluoropolymer-grade oleophobicity, and delivered PFAS-free by design, without the fluorochemistry now being regulated out in Australia.
Acid, the one it can't cover
Chemical, with the acid caveat
The Si-O-Si network is stable across roughly pH 1 to 11 at routine cleaning strength and short contact, so it holds through everyday cleaners: more resistant, never alkali-proof. The exception is acid on the stone itself. That is a separate physical mechanism no sealer prevents, and on a carbonate benchtop it is the honest limit, covered next.
Against the old ways
Why the surface beats the pore and the film.
Every dolomite seal you have been offered is one of two old classes, and each has a built-in flaw on a carbonate benchtop. A penetrating impregnator hides its repellency down in the pores, where daily wiping cannot reach it, so it fails from the inside out and repels water only, leaving oil to mark the stone. A film sits on top and is worse here still: it lays a plastic sheen over a stone chosen for its natural look, traps vapour, and a failed film has to be stripped back to bare stone before it can be redone.
Ours is the third way. It anchors into the surface and pore structure right where the finish gives it purchase, faces the wiping and spills head on, tops up on clean stone with no strip, and repels oil as well as water, so the marks that stay on a white benchtop lift off instead of soaking in. It is PFAS-free by design and colourless, so the white stays white. The full mechanism, pore versus surface, is in the four real-world resistances.
The limit, stated flat
No penetrating sealer stops acid etching.
Dolomite is carbonate. Acid etching is the reaction of carbonate with acid, a dissolution that physically removes material and leaves a dull micro-crater. It is not a stain, and it is correctable only by mechanical refinishing, never by cleaning. Because the acid reacts at the exposed surface and needs no pore penetration to do it, a penetrating sealer cannot prevent it. Sealing slows how fast liquids absorb and buys wipe-up time, which is real and worth having, but for an acid spill the answer is still a fast wipe.
This is the single most important thing to understand about super white dolomite, and it is why we grade it a moderate fit rather than a sweet spot, and why we will not sell it as stain-proof or permanent. It is also the exact place the quartzite mix-up costs owners: a real quartzite would resist the acid, and dolomite will not. The carbonate chemistry behind that limit is in stone and sealer chemistry. For the record, the one surface where we do make an etch-prevention claim is glass, a genuinely different mechanism, and it does not transfer to stone.
- Not permanent, not waterproof, not maintenance-free. A long-lasting treatment that degrades slowly and predictably and is renewed periodically.
- The finish decides the anchor. A denser polished dolomite gives the coating less to key into than a honed one. We assess your actual top and prepare it to suit before we seal.
- Beading fades before protection does. Contact angle reads only the top nanometre and is the fast clock, not proof the seal has failed. How the two clocks run, and the top-up that never strips, is in living with a sealed surface.
Specifier questions
The technical answers.
If there is no covalent bond to the carbonate, what holds it on?
Mechanical interlock into the pore structure, a self-condensed silica-like network with genuine Si-O-Si bonds inside the coating, and hydrogen bonding to the surface. On a carbonate stone the interlock is the dominant, load-bearing anchor, and it improves with open porosity. The missing piece is only the covalent bond to the carbonate itself, which is not how a surface repellent grips a stone like this.
How do I actually tell dolomite from quartzite?
Chemistry, not appearance, because they can look identical on a slab. Quartzite is silicon dioxide and is broadly acid-resistant. Dolomite is a calcium magnesium carbonate and reacts with acid. A drop of mild acid on a hidden offcut will fizz on dolomite and etch it, and do effectively nothing on quartzite. Never run that test on the installed top, since it will leave an etch mark. We can usually identify it at the quote.
Why is dolomite only a moderate fit?
Two reasons. It is a denser carbonate than a porous paver, so there is less open structure to anchor into, especially on a polished finish, and it still etches in acid, which no sealer prevents. It seals genuinely well against oil and staining, which is most of the day-to-day damage on a benchtop, so it is a real and worthwhile fit. It is graded moderate rather than optimal because of the density and the acid limit, not because the protection is weak.
What is the chemical resistance, exactly?
The Si-O-Si network is stable across roughly pH 1 to 11 at routine cleaning concentrations and short contact times: more resistant, not immune, and never alkali-proof or acid-proof. Acid etching of the dolomite itself is a separate mechanism that no sealing prevents. The four resistances and their honest bounds, with the test methods, are set out in the four real-world resistances.
Is it really PFAS-free, and does that cost oil performance?
It is PFAS-free by design, not by reformulating a fluorochemistry out. The trade-off is honest: fluoropolymers gave the lowest surface energy and the strongest oil repellency, so this does not match fluoropolymer-grade oleophobicity. What it does deliver is oil sitting on the surface and lifting in cleaning instead of soaking in, an outcome rather than a number. More on the PFAS story in living with a sealed surface.
Go deeper
The science behind the specifics.
This page is the dolomite delta. For the shared chemistry it draws on, follow the pillars.
Pillar · stone chemistry
Stone and sealer chemistry
Siliceous versus carbonate, and how the coating anchors into each mineral family. The full carbonate mechanism this page draws on. Read the pillar
Pillar · resistance
The four real-world resistances
Cleaning, chemical, UV and oil, with the honest bounds on each, and why protection at the surface beats a sealer buried in the pore. Read the pillar
Pillar · living with it
Living with a sealed surface
The two clocks, why the beading fades before the protection, the top-up that never needs stripping, and what no sealer can stop. Read the pillar
Plain English
Sealing dolomite
The same story without the chemistry: what super white dolomite needs, in plain terms. Read the guide
Everything else
The Sealing Library
Every common WA surface, by material, honestly graded. Find yours. Browse the library
Get a quote
Seal your dolomite with the next generation.
We will prepare and seal your super white dolomite with MineralProtect, registered under a 10-year guarantee, and tell you straight that the top is acid-sensitive before you book. Confirmed price up front.