Sodium Metasilicate for Alkaline Metal Degreasing

Producers of alkaline degreasers and metal pretreatment chemicals qualify a silicate slowly and then buy it for years. The reason is that the bath sits upstream of plating, phosphating or painting, so anything the raw material brings with it — iron, insoluble matter, an out-of-range particle size — surfaces later as a rinse residue or a coating defect. This page covers what has to be confirmed before a grade is proposed, and where the limits of what we will claim actually sit.

Updated September 23, 2026

Short answer

Anhydrous sodium metasilicate is the common choice for alkaline degreasing and metal pretreatment concentrates, where a high active per kilogram and low water content matter; pentahydrate is used where a milder dissolution profile suits the make-up method. Because the bath sits upstream of plating, phosphating or painting, iron and insoluble matter are the indicators that decide qualification — both grades offer Superior Fe ≤0.010% and are quoted against your own limits, with batch traceability from raw-material lot to finished bag.

How Sodium Metasilicate Is Used

Alkaline soak and spray degreasing baths for steel components
Pretreatment lines feeding phosphating, plating or paint systems
Buffering component in built alkaline cleaner concentrates
Electrolytic and ultrasonic cleaning formulations
Rust-preventive alkaline wash stages between machining operations

Benefits for This Industry

Low-iron requirements reviewed against the grade specification before quotation rather than after the first delivery
Water-insoluble matter controlled per grade, which is what governs rinse residue on the finished part
Defined mesh range so bath make-up dosing stays repeatable across deliveries
Batch numbers carried through COA and retained samples, so a bath excursion can be traced to a specific lot
Change notification on specification or process changes, so a requalification is never a surprise found in the incoming inspection
Continuous-batch COA history available before the first order, so consistency can be checked against your internal control limits

How Our Sodium Metasilicate Supports This Application

Formulation need	Product feature	Value to your line
High active, low water in the concentrate	Anhydrous grade	More active per kilogram for pretreatment concentrates
Clean rinse ahead of plating or paint	Iron ≤ 0.02% with controlled water-insoluble matter	Less residue that would become a coating defect downstream
Milder make-up dissolution profile	Pentahydrate hydrated grade	Controlled dissolution where the make-up method needs it
Trace a bath excursion to its source	Batch numbers through COA and retained samples	A bath problem traces back to a specific lot
No surprise requalification	Advance change notification on specification or process	Requalification is never first found at incoming inspection

Blending and dosing hoppers on the production line.

Batch samples analysed in the quality-control laboratory — Batch samples analysed before release against the grade spec.

Finished goods staged as FIBC jumbo bags in the warehouse — Finished goods staged as 1,000 kg FIBC jumbo bags.

What We Need to Confirm Before Recommending a Grade

Grade selection for this application depends on your process, not on a catalogue number. Send these conditions with your enquiry and the recommendation comes back with the reasoning attached.

Substrate: Steel, galvanised, aluminium, brass or a mixed line — this is the first question, not a detail.
Bath conditions: Make-up concentration, operating temperature and working pH range of the degreasing stage.
Iron and insolubles limits: Your internal control limits for Fe and water-insoluble matter, and the test method behind them.
Particle size and dissolution: Mesh range and how the bath is made up — manual charging, automatic dosing or pre-dissolved concentrate.
Rinse and residue requirement: What the downstream stage tolerates, since plating and paint adhesion are decided by what survives the rinse.
Qualification plan: Coupon test method, trial batch size and the framework volume once the material is approved.

What this page does not claim

Performance in your formulation is established by your own trial, not by a supplier page. These are the limits we hold to.

We do not warrant compatibility with aluminium, zinc or other amphoteric metals. Strong alkali attacks these substrates, and any use on them must be established by your own coupon testing at your bath conditions.
No corrosion-inhibition performance is claimed. Where a formulation relies on inhibition, that has to be demonstrated in your system.
We supply the specification, the batch data and the test method — not a conclusion about your bath. Substrate compatibility is determined by your coupon test.
We do not recommend a bath formulation or dose rate on the strength of an industry name alone; process conditions come first.
Low-iron supply is confirmed per order against current production, not offered as an always-in-stock catalogue item.

Anhydrous is the common choice where a high active per kilogram and low water content in the concentrate are wanted; pentahydrate is used where a milder dissolution profile suits the make-up method. Both are quoted against your iron and insolubles limits rather than against a generic grade name. Send the substrate, bath conditions and current specification and we will tell you which grade to put on the coupon test.

Confirm grade, monthly quantity, packing, destination port and buyer type on the RFQ form.

Ready to RFQ metal-degreasing grade

Prefer anhydrous for many degreasing formulas — confirm iron and insolubles. Include monthly MT, packing and port.

Grade
Monthly quantity (MT)
Packing
Destination port
Documents needed

Request quote Open anhydrous product

FAQ

Can this be used on aluminium parts?

Not on our say-so. Sodium metasilicate is strongly alkaline, and aluminium and other amphoteric metals are attacked by strong alkali — some formulators do use silicate-built cleaners on aluminium precisely because silicate moderates that attack, but whether it is adequate depends on your alloy, concentration, temperature and contact time. Establish it with a coupon test at your own bath conditions. We will supply the material and the test method; we will not supply the conclusion.

What iron level can you hold?

Iron is controlled to the published grade specification and reported on every batch COA. If your internal limit is tighter than the standard grade, send the figure and the test method with your enquiry — low-iron supply is confirmed against current production per order rather than assumed.

Why does water-insoluble matter matter here?

Insolubles are what remain on the part after the rinse. In a line feeding plating or paint, that residue shows up as an adhesion or appearance defect several stages downstream, which is why pretreatment buyers hold a tighter limit than detergent buyers do.

Will you tell us before you change anything?

Yes — that is the point of agreeing change control at qualification rather than after. State in the RFQ that advance notification of specification or process change is required, and it is recorded against the account. Unannounced change is the most common reason a qualified supplier gets requalified out.

Can we trace a bath problem back to a specific batch?

Yes. Batch numbers run through the COA, the retained sample and the packing marks. Send the batch number, the COA, photographs of the received goods and your test method, and the retained sample from that lot can be re-tested against the release data.

How much material do we need for qualification?

A laboratory sample is enough for the initial coupon work. Beyond that it depends on your bath volume — send the trial plan with your enquiry and the sample and first trial quantity can be quoted together, rather than treating the trial as a separate negotiation.