In short: Untreated matting silica has a bare, water-loving surface; treated grades carry an organic or specialised surface layer added after production. The treatment changes how easily the powder wets out, how it behaves in a waterborne versus a solvent-based resin, how hard it settles in the can, and how the film feels. It changes the trial more than it changes the gloss.
A precipitated silica leaves the plant with a surface covered in silanol groups. That surface is strongly water-loving: it wets out readily in water, hydrogen-bonds with anything that will hydrogen-bond back, and holds moisture from the air. Left as it is, the powder is described as untreated.
A treated grade has had something added to that surface after production — an organic layer in the case of grades meant for solvent-based and resin-rich systems, or a different, specialised treatment for grades intended to disperse and stay stable in waterborne systems. The particle underneath is broadly the same family of material. What changes is the outermost few molecules, and what those molecules prefer to touch.
In our own range that distinction runs through the coating matting family: CENSIL 560N is the untreated grade, CENSIL 525L is organically treated for resin compatibility, and CENSIL 230W carries a treatment aimed at waterborne systems. Same family, one gradient, three different surfaces.
Wetting is the first place you see it. An untreated silica dropped into a solvent-based resin tends to resist wetting: the powder floats, agglomerates persist, and the mill has to do the work of breaking them down. The same powder in a water-based system wets almost eagerly. A treated grade reverses that behaviour in proportion to how much treatment it carries.
This shows up on your line as mill time and as grind quality. If a candidate needs noticeably longer to reach your normal grind reading, the treatment is probably mismatched to the medium rather than the grade being wrong in some absolute sense. Before you reject it, try its sibling with the other surface.
It also shows up as seeds and specks in the finished film. Under-dispersed agglomerates do not disappear when the film dries — they sit in it, catch the light, and get reported back as a quality complaint that looks nothing like a matting problem.
Waterborne coatings have been the main driver of treated matting grades, because the constraints are tighter. The binder is dispersed rather than dissolved, the system is more sensitive to anything that shifts its stability, and the film forms by coalescence rather than by solvent leaving.
An untreated silica in a waterborne system disperses easily — that is not the problem. The problem is what it does over the following weeks: thickening, settling, or a shift in the way the film coalesces that shows up as a change in feel or in water resistance. A grade treated for waterborne use is designed to keep that from drifting.
This is why a matting grade that performs beautifully in your solvent-based line is a poor starting point when you convert that line to water. It is not a formulation you adjust; it is a different grade.
Usually, yes — and the difference is easier to feel than to measure. Treated grades tend to give a smoother, more closed surface feel; untreated grades tend to read as drier or more open under the fingertip. Neither is better. Furniture makers in one market want the silky hand; makers in another want the dry, matte-paper feel, and will reject the other one.
Haze on a clear film is the other place it shows. Surface treatment affects how well the particle's refractive behaviour is hidden inside the binder, and small differences there are highly visible over a dark substrate. Any trial that includes a clear coat has to include a haze panel over black, or it has not tested the thing most likely to fail.
Settling behaviour differs too. The treatment influences whether the sediment that forms after weeks in a sealed can is a soft bed that stirs back in, or a hard cake that does not. That is a storage test, not a bench test, and it is the reason benchmark trials take a month.
Run both. The efficient way to find out is not to reason about it — it is to put a treated and an untreated grade beside your incumbent in the same resin, at the same loading, on the same day, and let the panels tell you. The extra work is one more draw-down; the information is the entire answer.
Judge them on the five properties that decide a matting substitution: gloss at 60° and 85°, haze and clarity on a clear film over a dark substrate, tactile feel, dispersion effort and viscosity, and settling after a month in a sealed can at ambient and elevated temperature.
Then keep the loser's data. The grade that loses your clear-coat trial is frequently the right grade for the pigmented system running on the next line, where haze does not matter and dispersion effort does. Most plants end up using more than one matting grade for exactly this reason.
W denotes a grade treated for waterborne systems, L an organically treated grade for resin compatibility, and N an untreated grade. The letters describe the surface, not the fineness.
No. Treatment is a match, not an upgrade. An untreated grade is the right answer in plenty of systems, and it is often easier to disperse in water. The question is which surface suits your medium and the finish your customer expects.
You can disperse it, which is why people try. Whether it stays stable, keeps the film clear and avoids hard settling over weeks of storage is a different question, and it is the one the trial has to answer. Start instead from a grade intended for waterborne systems.
Draw the same clear coat with and without the matting agent over a black panel. If the unmatted film is clear and the matted one is milky, the matting agent is implicated. If both are hazy, look at the resin, the coalescent, the film thickness or the cure.
Third-party product and brand names are the trademarks of their respective owners and are used here only to identify the reference points customers benchmark against. No equivalence, affiliation or endorsement is claimed or implied.
The material you use now, the formulation or resin, the equipment and the target you need to hit. That is enough for us to say whether we have something worth testing.
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