How to Choose a Degreaser: Alkaline, Neutral, Solvent-Based and Electrolytic Degreasing Chemicals

admin — Mon, 02 Nov 2026 06:05:33 +0000

Choosing a degreaser comes down to four questions: what metal the part is made of, what type of oil is on the surface, what equipment does the cleaning, and what process the part goes to next. Answer these four correctly and the product group selects itself; answer them wrong and even the most expensive chemical will cause paint blistering, coating failure or darkening on aluminium.

What is a degreaser?

A degreasing chemical (degreaser) removes organic soils — cutting oil, soluble (boron) oil, drawing and stamping oils, grease, hydraulic oil, protective oil film and polishing paste — from the surface of metal and plastic parts. Industrially it is made in three main families: water-based alkaline and neutral products, solvent-based products, and the electrolytic degreasers used on plating lines. Most water-based products are sold as concentrates and used diluted at 2–10%.

Types of degreaser

Alkaline degreasers

The most common group. They perform strongly under heavy oil and grease loads on steel, stainless steel and cast iron, working at 40–80 °C in immersion, ultrasonic and spray washing. Highly alkaline products can etch and dull aluminium, zinc and brass; for these metals, inhibited or low-alkaline products should be chosen.

Neutral and mildly alkaline degreasers

Used on sensitive metals such as aluminium, magnesium, copper, brass, gold and silver. They minimise the risk of staining and darkening and typically work at 30–60 °C. Under heavy oil loads, time and temperature are increased or ultrasonic support is added.

Demulsifying (oil-splitting) degreasers

Instead of holding the oil in the bath as an emulsion, they release it to the surface. The oil is removed with a skimmer or separator; bath life is extended and chemical consumption and waste cost fall. Preferred on high-oil-load continuous production lines and in ultrasonic baths. Emulsifying products, by contrast, are advantageous under low oil loads and in critical cleaning specifications. See Industrial Degreasing Methods for detail.

Low-foam degreasers for spray washing

In spray and tunnel washers, foam causes pump cavitation and overflow. These lines need products specially formulated to be low-foaming; an immersion product must not be used in a spray machine. See Cleaning Chemicals for Spray Washing Machines.

Solvent-based degreasers

Used on water-sensitive parts, on lines where drying is not possible, for very short cycle times and in maintenance cleaning. Modern solvent-based products have replaced chlorinated solvents; high-flash-point and low-odour options are available. They can be recovered and reused in closed solvent machines. See Solvent Cleaning Selection Guide.

Hybrid (water–solvent) degreasers

They combine the safety of a water-based product with the dissolving power of a solvent. Used in manual and spray application, on large parts that are hard to dry, and on sensitive surfaces that require low conductivity.

Electrolytic degreasers

The final activation step before plating on galvanising, nickel and chrome lines. Gas bubbles formed at the surface under current remove micro-level oil and clinging soil that alkaline cleaning cannot reach. Selected to run anodic, cathodic or bidirectional.

Selection table: by metal, oil type and equipment

Situation	Suitable degreaser
Steel and cast iron, heavy grease and cutting oil	Alkaline, demulsifying
Stainless steel, soluble oil after CNC	Alkaline or mildly alkaline, ultrasonic-assisted
Aluminium and its alloys	Neutral or inhibited mildly alkaline
Copper, brass, zinc die-cast (zamak)	Neutral, with anti-staining
Gold, silver, jewellery parts	Neutral, effective on polishing paste
Spray and tunnel washing machine	Low-foam alkaline or neutral
Water-sensitive part, no drying	Solvent-based or hybrid
Final step before plating	Electrolytic degreasing
Before paint and powder coating	Alkaline or neutral, followed by good rinsing

Five points to watch in selection

Metal compatibility: The product label or technical data sheet should clearly state your part material as “suitable”. A “limited compatibility” note is a risk in series production.
Oil type: Mineral oil, synthetic oil, emulsion-type coolant and calcium-soap greases each call for a different product. Give the technical team the oil’s name and, if available, its safety data sheet.
Equipment: Immersion, ultrasonic, spray and manual application each demand different foam behaviour and temperature. For ultrasonic baths, Chemical Selection in Ultrasonic Cleaning is a useful guide.
Next process: Paint, coating, welding or assembly; rinse quality and temporary corrosion protection are set accordingly.
Waste and bath life: Oil separation, concentration tracking (titration) and the bath change interval directly affect cost.

How is a degreaser used?

The concentrate is diluted with water at the ratio given in the technical data sheet; temperature and time are set by the part and oil load. After cleaning, at least two rinse stages are used and the part is dried without waiting. On carbon steel, rust starts if drying is delayed; in that case a rust preventive is added to the rinse water or a corrosion-inhibited product is chosen. Bath concentration is monitored weekly by titration. For soluble oil and carbonised residues on CNC parts, see Cleaning Cutting Oil, Coolant and Carbonised Residues.

How is cleaning verified?

The water-break test is the most practical check: the water film on the part leaving the rinse should stay unbroken. Before painting and bonding, surface energy is checked with test inks; in technical cleanliness specifications, gravimetric residue measurement is used.

Frequently asked questions

Which is the best degreaser?

There is no single “best” product. For heavy oil on steel an alkaline demulsifying product, on aluminium a neutral product, and in a spray machine a low-foam product give the best result. The choice is made by metal, oil type and equipment.

Which degreaser is used for aluminium?

Neutral or inhibited mildly alkaline products. Highly alkaline products etch and dull aluminium.

At what temperature does a degreaser work?

Alkaline products mostly work at 50–80 °C, neutral products at 30–60 °C, and solvent-based products at room temperature. Low-temperature formulas reduce energy cost.

Is a degreaser the same as a rust remover?

No. Degreasers remove organic soils (oil, grease); rust removers are acidic and remove oxide and rust. Usually degreasing is done first, then rust removal.

Which degreaser should be used in an ultrasonic bath?

Low-foam alkaline or neutral products formulated for ultrasonics that do not suppress cavitation. Spray and immersion products are not always suitable for an ultrasonic bath.

When is a solvent-based degreaser preferred?

When the part cannot contact water, when drying is not possible, when the cycle time is very short, or when on-site cleaning is needed in maintenance and repair.

Molkim degreasers

Molkim offers alkaline, neutral, demulsifying, low-foam, solvent-based, hybrid and electrolytic degreasers. All products are delivered with a KKDİK- and CLP-compliant safety data sheet and technical data sheet. Share your part material, oil type and equipment; our laboratory will run a sample trial and determine the suitable degreaser and working parameters together with you.

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