| HS Code | 222866 |
| Product Name | Rayalaseema Caustic Soda Flakes |
| Chemical Formula | NaOH |
| Cas Number | 1310-73-2 |
| Molecular Weight | 40.00 g/mol |
| Appearance | White flakes |
| Purity | 98% min NaOH |
| Grade | Technical Grade |
| Melting Point | 318°C (604°F) |
| Boiling Point | 1,388°C (2,530°F) |
| Solubility In Water | 111 g/100 mL at 20°C |
| Specific Gravity | 2.13 at 20°C |
| Ph 1 Solution | Approximately 13 |
As an accredited Rayalaseema Caustic Soda Flakes factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Rayalaseema Caustic Soda Flakes are packed in 25 kg HDPE woven bags with an inner polythene liner for safe, dry handling. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with Rayalaseema Caustic Soda Flakes, securely packed in moisture-proof bags, palletized, and ventilated for safe transport. |
| Shipping | Rayalaseema Caustic Soda Flakes ship as UN 1823 (sodium hydroxide, solid), Class 8 corrosive. Packed in 25/50 kg HDPE bags, palletized and shrink-wrapped, then placed in sealed, dry containers. Avoid moisture, acids, and aluminum. Full hazmat documentation, placarding, and IMDG/ADR compliance are required. Handle with protective equipment to prevent skin and eye damage. |
| Storage | Store Rayalaseema Caustic Soda Flakes in a cool, dry, well-ventilated area in tightly sealed, corrosion-resistant containers. Keep away from moisture, water, acids, and incompatible materials. Store off the floor on pallets to prevent dampness, and isolate to avoid physical damage. Use appropriate PPE when handling. |
| Shelf Life | Shelf life is approximately 24 months when stored in sealed, dry conditions away from moisture, humidity, and air exposure. |
Bauxite digestion in an alumina refinery begins with the dissolution of Rayalaseema caustic soda flakes in weak spent liquor rather than in raw water; this sequence lowers the exothermic spike that occurs when flake contacts untreated water and stabilises the initial free caustic concentration before the slurry enters the digestion circuit. The dissolving vessels are fabricated from A240 Type 316L stainless steel, fitted with draft-tube agitators and vented to caustic scrubbers, and the resulting liquor is held at 170–260 g/L Na₂O equivalent before blending with ground bauxite. For laterite-grade bauxite, the charged alumina-to-caustic ratio is commonly 0.30–0.55, while karst bauxite operations maintain 0.55–0.75, with the selection governed by reactive silica, organic carbon carryover, and available digestion time. Boehmitic bauxite is processed at 210–250°C and 28–34 bar with free caustic at 180–240 g/L Na₂O, whereas diasporic bauxite demands 245–280°C, 250–300 g/L Na₂O, and multi-stream tubular reactors designed for higher pressure duty.
Desilication is the most significant caustic loss mechanism in digestion. Reactive silica in bauxite reacts with sodium aluminate and sodium hydroxide to form sodalite-type sodium aluminosilicate scale, consuming approximately 0.70–1.0 kg Na₂O and 0.35–0.60 kg Al₂O₃ per kilogram of reactive silica. Where bauxite contains more than 4% reactive silica, the slurry is pre-desilicated at 90–100°C for 6–8 h after contacting recycled spent liquor; this step converts silica to desilication product before the slurry enters the main heater and prevents hard scale formation on tube walls. Digestion discharge is flashed from 240–280°C to 105–110°C through a pressure letdown train, then the red mud is separated in high-rate thickeners with rake speeds at 1–2 rpm. Clarified sodium aluminate liquor is cooled, filtered through sand filters and polish filters, and directed to precipitation, where seed alumina hydrate is added in a continuous circuit. A drop in precipitation yield is often the first production-line indication of caustic imbalance, appearing before bulk liquor chemistry alarms because supersaturation shifts rapidly when free Na₂O fluctuates more than ±5 g/L against the target charge.
Typical operating ranges for Bayer digestion are reported in the following comparison. These ranges represent design data used in refinery feasibility studies and are not process guarantees for any single bauxite shipment.
| Digestion parameter | Boehmitic bauxite range | Diasporic bauxite range | Measurement method |
|---|---|---|---|
| Free NaOH concentration | 180–240 g/L Na₂O | 250–300 g/L Na₂O | ASTM E291-18 |
| Alumina-to-caustic ratio | 0.55–0.70 | 0.60–0.75 | mass balance titration |
| Digestion temperature | 210–250°C | 245–280°C | process thermocouple |
| Reactor pressure | 28–34 bar | 38–52 bar | pressure transmitter |
| Pre-desilication time | 4–6 h at 90–100°C | 6–8 h at 95–105°C | residence-time calculation |
Chloride and iron impurities in the caustic feed influence downstream corrosion and colour. Rayalaseema caustic soda flakes are supplied as white deliquescent solids conforming to the general requirements of ASTM E291-18 and Indian Standard IS 252:2013 for commercial sodium hydroxide; typical flake specifications are not less than 98.5% NaOH, not more than 0.5% NaCl, and not more than 0.005% Fe₂O₃ by mass. In Bayer liquor, chloride ions accumulated from feed caustic and raw water contribute to pitting corrosion in A240 Type 304L and 316L digesters when chloride exceeds 4–6 g/L at high temperature, so refineries using seawater-borne bauxite or brackish makeup water often select higher-alloy digestion heaters or duplex stainless steel. Flake addition must be controlled to avoid local pockets of high alkalinity because such pockets cause precipitation of monosodium aluminate and reduce recovery. The dissolution station is therefore designed with bag-splitting hoods, dust extraction, and vacuum transfer systems to keep airborne caustic below the occupational exposure limit of 2 mg/m³ ceiling for sodium hydroxide mist.
Cotton mercerization requires a sodium hydroxide bath in which cellulose fibres swell under controlled tension, producing a lattice transition from cellulose I to cellulose II that improves lustre, dye uptake, and dimensional stability. Rayalaseema flake is used when local water contains high bicarbonate hardness, because dilution of diaphragm-grade liquid alkali with hard water precipitates calcium carbonate and magnesium hydroxide as sludge in the saturator and complicates removal from the mercerizing range. The working bath is maintained at 18–25°C and 20–28°Bé, corresponding to 220–310 g/L NaOH. Tension is controlled at 2–4% positive extension relative to grey fabric during the 45–90 s impregnation window; excessive tension compacts amorphous regions and reduces dye uptake, while insufficient tension fails to orient the fibre bundle. Bath replenishment is monitored by continuous conductivity and density, and the ratio of free NaOH to sodium carbonate is held above 30:1. Carbonate accumulation above 1.0% of total alkali produces dulling, uneven dye adsorption, and scale in the tenter-chain caustic recovery unit.
Iron in the caustic feed must remain below 15 mg/L in the bath to avoid yellow staining on optically brightened white goods; low-iron flake is filtered through 25 µm candle filters before entering the impregnation box. Wetting agents with an HLB of 10–13 and resistance to 250 g/L NaOH are injected at 0.05–0.2% volume fraction to displace air from yarn capillaries, since air bubbles cause unswollen core zones that appear as dye-resistant streaks. After impregnation the fabric passes through a hot-water recovery section at 70–90°C, then through two-stage counter-current displacement baths. Weak wash water is directed to an evaporator and recovered 12–15% NaOH is returned to the saturator. Process release tests include ISO 105 C06 for colour fastness to washing and AATCC 150-2022 for dimensional change; cotton knitgoods processed at 25°Bé without stabilisation commonly show width shrinkage above 5% after five home laundering cycles, whereas substrate mercerized under 2.5% positive tension and neutralised to pH 6.8–7.2 retains shrinkage below 2%. The process is confined to cellulosic fibres; wool, silk, acetate, and polyamide are degraded by strong alkali. Polyester-cellulose blends are mercerized with ambient caustic and the dwell time is limited to 40–60 s to avoid surface hydrolysis of the polyester component.
In open steam-jacketed kettles, Rayalaseema caustic soda flakes are pre-dissolved into a 38–43°Bé lye solution at 70–85°C before fat addition. The aqueous phase is introduced first, flake is added incrementally under agitation, and the batch is cooled to 70±5°C before oil charging to prevent local lye pockets that cause grainy neat soap. Stoichiometric alkali is calculated from the saponification value of the oil blend plus a 0.2–0.5% free alkali reserve; for a palm kernel/coconut blend with saponification number 250–260 mg KOH/g, total NaOH requirement is 178–185 g/kg oil at 100% purity. Saponification proceeds at 80–95°C under high-shear recirculation at 1200–1500 rpm. Spent lye and glycerine are separated by adding 5–7% sodium chloride to salt out the neat soap. Free alkali in the neat soap is controlled to 0.05–0.15% as NaOH to avoid rancidity and skin irritation, with analysis by ASTM D460. Production-line failure commonly appears as pseudo-gel formation when the batch temperature drops below 75°C and lye concentration exceeds 30°Bé; the resulting viscous paste reduces heat transfer and slows salt-out separation.
For unsaturated oil feedstock, the kettle is blanketed with inert gas and temperature is kept below 100°C to limit oxidative rancidity. Iron and copper contamination must be avoided because they accelerate discolouration in tallow-based soaps. Flake caustic containing sodium chloride above 0.5% may be tolerated in laundry soap manufacture but is undesirable in transparent soap production, where chloride dulls clarity and changes viscosity. Glycerine recovered from the spent lye stream after saponification is clarified and evaporated under vacuum at 55–65°C to maintain colour, and the spent lye is nitrogen-stripped to remove dissolved air before re-use.
Open recirculating cooling systems treating makeup water with total alkalinity above 180 mg/L as CaCO₃ receive Rayalaseema caustic soda flakes as a 0.1–0.5% solution injected after the blowdown valve. The addition point is a side-stream mixing loop with residence time below 20 s and a pH probe positioned 3–5 m downstream. System pH is maintained between 7.8 and 8.5 for polyphosphate-based inhibitors, and between 8.3 and 9.0 for silica control programs, with continuous pH measurement per ASTM D1293-18. Dosing above pH 9.0 on high-hardness water induces calcite deposition on heat exchanger tubes and should be avoided unless a scale inhibitor containing 1-hydroxyethylidene-1,1-diphosphonic acid is present at 4–10 mg/L active. Caustic soda is incompatible with aluminium components, zinc galvanising, and carbon steel at high pH; injection lines are constructed from AISI 316L or PVC-U. For potable water pH correction, compliance with NSF/ANSI 60 and maintenance within the WHO pH range of 6.5–8.5 are normally required. The same flake solution is directly dosed into wastewater neutralisation basins, but the reaction must be performed with diffused aeration because carbon dioxide absorption accelerates when the pH rises above 8.0 and can cause uncontrolled carbonate sludge formation.
Kraft mills use caustic soda flakes for white liquor adjustment after the recausticizing loop and for alkaline extraction in the bleach plant. In the recausticizing plant, smelt from the recovery boiler is dissolved in weak wash and the resulting green liquor is treated with calcium oxide to regenerate white liquor; causticizing efficiency is the proportion of sodium carbonate converted to NaOH. When efficiency falls below 78%, flake caustic is added to the white liquor storage tank to adjust effective alkali before chip impregnation. The addition point is critical: caustic is dissolved in condensate at 40–50°C and metered into the suction side of the white liquor transfer pump, never directly into hot liquor at 85–95°C, because local boiling can release caustic aerosol and cause carbonate precipitation. Effective alkali charge for softwood pulping is 14–20% NaOH on oven-dry wood with sulfidity at 25–35%; hardwood pulping commonly uses 12–16% NaOH at 20–25% sulfidity. H-factor, the integral of reaction temperature with time over the delignification period, is operated between 1200 and 1800 for softwood to reach kappa number 20–30, measured by TAPPI T 236 om-13 or ISO 302:2015.
In the oxidative extraction stage of the bleach plant, caustic soda at 0.8–1.5% on pulp is combined with oxygen and hydrogen peroxide to dissolve degraded lignin fragments. The extraction tower at 80–90°C and pH 10.5–11.5 must retain a residual NaOH concentration of 0.05–0.20 g/L at the discharge; deficiency below this range increases COD carryover to the chlorine dioxide stage, while excess alkali reduces pulp viscosity. Production-scale equipment includes upflow towers with 60–90 min retention and medium-consistency pumps operating at 10–14% pulp consistency with shear rates low enough to prevent fibre shortening. Caustic addition to hypochlorite bleach must be tightly controlled because sodium hypochlorite reacts with NaOH and promotes chlorate formation at pH above 9.5. Aluminium components in the bleach plant and black liquor carryover into the extraction stage are the main incompatibility risks; conductivity-based leak detection in the brown stock washer prevents contamination of the pulp mat before caustic extraction.
Chemical synthesis using Rayalaseema flakes often begins with dissolution in methanol to form sodium methoxide, a catalyst for biodiesel transesterification and alkoxide synthesis. The reaction NaOH + CH₃OH ⇌ NaOCH₃ + H₂O is driven by the removal of water; at atmospheric pressure methanol boils at 64.7°C, and the water-methanol azeotrope at 96.4% methanol cannot be separated by simple distillation. Industrial production therefore uses a continuous distillation column with molecular sieve dehydration or a pervaporation membrane to hold water in the sodium methoxide product below 0.5%; otherwise the catalyst hydrolyses triglycerides and lowers ester yield. Flake is added intermittently to methanol at 25–35°C, with the dissolution exotherm controlled by cooling to keep the bulk temperature below 50°C. The resulting 25–30% sodium methoxide solution is stored in carbon steel or stainless steel under nitrogen, and moisture ingress is checked by Karl Fischer titration. In biodiesel plants the catalyst dose is 0.3–1.0% by mass of oil, with reactor temperature 55–65°C and residence time 1–2 h; glycerine phase separation is delayed by soap formation when water in the methoxide exceeds 0.4%. Published data for specific sodium methoxide configurations using Rayalaseema flakes is limited; the stated ranges reflect general industrial practice for solid caustic dissolution in methanol.
Caustic scrubbers charged with 10–20% NaOH solution neutralise acid gases such as HCl, SO₂, and Cl₂ from process vents. Flake caustic is dissolved in a dedicated polyolefin or fibre-reinforced plastic vessel, and the solution is recirculated through packed towers at pH 9.5–11.5 with oxidation-reduction potential monitoring. Hypochlorite formed from chlorine absorption must be kept below 15 g/L available chlorine to avoid exothermic decomposition; storage temperature is kept below 35°C. Titanium and nickel are used in scrubber internals where hypochlorite is present; carbon steel is unsuitable below pH 10. The same prepared solution is used for hydrolysis of methyl chlorosilanes in silicone intermediate production, but the rate of flake addition is limited by hydrogen evolution and the need to maintain a closed vent to an emergency scrubber.
CIP skids in dairy, brewery, and pharmaceutical process lines prepare a 1–3% NaOH solution from Rayalaseema flakes, with the working solution held at 70–85°C and circulated for 15–30 min per wash cycle. Detergent dose is controlled by conductivity with setpoint 25–50 mS/cm, and the return line is fitted with a turbidity sensor; caustic concentration in the rinse is verified by ASTM E291-18. Sequestering agents such as sodium gluconate at 0.1–0.3% or EDTA at 0.05–0.2% are required in hard water above 150 mg/L CaCO₃ to prevent scale. The caustic phase is never introduced to aluminium brewing vessels, tin-lined copper, or glass-lined equipment rated below pH 12; fluorocarbon-lined pumps handle hot caustic. In bottle washing, 2.5–4.0% NaOH at 60–75°C is applied with spray pressure 1.5–2.5 bar and residence time 8–12 min; caustic carryover is monitored by pH and conductivity in the final rinse. Flake dissolution before the CIP tank is mandatory because undissolved flake can impinge on pump impellers and cause local cavitation, and batch-to-batch variance in flake wetting can extend dissolution time if the water temperature falls below 30°C.
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Rayalaseema Caustic Soda Flakes is a white deliquescent solid form of sodium hydroxide supplied as irregular lamellar particles from rotary drum flaking of membrane-cell caustic concentrate. The product is identified by lot-specific certificate of analysis rather than by a discrete model designation; standard commercial procurement references minimum total alkali of ≥ 99.5% w/w NaOH on a dry basis, sodium carbonate ≤ 0.4% w/w, and sodium chloride ≤ 0.05% w/w. Analytical verification is performed in accordance with ASTM E291-18 for total alkalinity, chloride, and sulfate determinations, with sample handling conducted under sealed-vial or nitrogen-assisted conditions to limit atmospheric CO₂ ingress. The flakes have a bulk density generally within 0.80–1.05 g/cm³ and a mass loss on drying below 1.0% w/w at 105 °C to constant mass. Packaging comprises 25 kg or 50 kg woven polypropylene bags with polyethylene inner liners, marked as UN 1823, Class 8, Packing Group II, with CAS number 1310-73-2.
The production technology determines chloride, chlorate, and trace metal residuals that ultimately influence corrosion, filtration, and catalyst behaviour in downstream processing. Membrane-cell caustic flakes comparable to Rayalaseema material are characterised by low sodium chloride and chlorate residuals relative to diaphragm-cell material. When the flakes are used in rayon production, chloride concentrations at ≤ 0.05% w/w reduce chloride-induced stress corrosion risk in nickel-based dissolution equipment. Diaphragm-cell caustic with chloride in the range 0.3–1.0% w/w frequently requires additional treatment or alloy adjustment. Chlorate residuals in membrane-cell material are typically ≤ 10 mg/kg, which is significant in chloralkali-intensive applications because chlorate can accumulate in recirculating process liquors. The following ranges are based on published industrial data for membrane-cell flake caustic and are used as procurement screening limits; actual lot-specific certificates control the supply.
| Parameter | Membrane-cell flake | Diaphragm-cell flake | Mercury-cell liquid |
|---|---|---|---|
| NaOH total alkali | ≥ 99.5% w/w | 99.0–99.5% w/w | 99.0–99.5% w/w |
| Sodium chloride | ≤ 0.05% w/w | 0.3–1.0% w/w | ≤ 0.05% w/w |
| Sodium carbonate | ≤ 0.4% w/w | ≤ 0.5% w/w | ≤ 0.3% w/w |
| Chlorate as NaClO₃ | ≤ 10 mg/kg | ≤ 100 mg/kg | ≤ 20 mg/kg |
| Iron | ≤ 20 mg/kg | ≤ 30 mg/kg | ≤ 10 mg/kg |
In alumina refineries, the flakes are dissolved in recirculating spent liquor to maintain Bayer digestion circuits at 200–240 g/L Na₂O equivalent. Addition through dedicated causticisers or recirculation loops is standard because direct open addition to hot vessels can produce local temperature excursions above 80 °C from the hydration enthalpy of NaOH. In pulp and paper operations, reconstituted flakes are used for oxygen delignification extraction and alkaline stage control, with the solid material preferred where water freight costs favour anhydrous delivery. Field inspection of bulk bag unloading stations indicates that torn inner liners and moisture-induced caking are the predominant lot-rejection conditions; caked flakes should be removed from the feed path rather than broken into the dissolver to avoid undissolved solids entering downstream metering pumps.
Substitution of Rayalaseema Caustic Soda Flakes for 48% w/w membrane-cell liquid caustic alters logistics, heat balance, and particulate filtration more than alkalinity equivalence. The dissolution of solid NaOH in water releases −44.5 kJ/mol, and the resulting temperature rise can exceed 60 °C depending on final concentration and feed water temperature. Makeup tanks should be constructed of carbon steel or type 316L stainless steel and fitted with external cooling or recirculation. For textile mercerization, the flakes are dissolved to 20–22 °Bé NaOH, equivalent to approximately 18–20% w/w, for cotton swelling and lubrication under tension. Fine undissolved flake particles can create uneven fibre swelling, so an in-line filter with 200 μm mesh is placed downstream of the caustic dissolver. When the flakes replace liquid caustic in pulp extraction stages, the solid must be reconstituted to 10–18% w/w NaOH stock solution before injection into the oxygen delignification filtrate loop; direct flake addition into the alkaline stage is not recommended because of excessive carbonate precipitation and poor local mixing. The use of flakes rather than 48% lye reduces inbound water mass by approximately 52% per unit of NaOH, but requires dedicated flake handling, dust suppression, and dissolution equipment.
Material selection for caustic flake dissolution systems follows concentration and temperature boundaries. At temperatures below 50 °C and NaOH concentrations up to 30% w/w, carbon steel is generally acceptable for storage tanks; at 80 °C and above, unstabilised carbon steel in high-caustic service is susceptible to caustic stress corrosion cracking. Nickel, nickel alloys, and type 316L stainless steel are specified for heater tubes, thermowells, and valve trim. Titanium is avoided in hot concentrated caustic because of hydrogen uptake and potential hydride formation. The flakes must be added to water, not water to flakes; reverse addition can produce a surface crust, local hot spots, and vigorous spattering. Agitation in the dilution vessel should maintain a minimum tip speed of 0.5 m/s to prevent settled solids from forming a hard heel. Reconstituted caustic solution is transferred through schedule 80 steel piping or lined FRP piping; flex hoses are minimised and must use chemically resistant gaskets such as PTFE or EPDM. In production-scale batch mixers, the flake feed hopper must be kept under nitrogen purge and positive differential air pressure to reduce surface hydration and CO₂ absorption.
Charging Rayalaseema Caustic Soda Flakes into organic synthesis reactors requires control of free water before addition. Residual water in the reactor or solvent is consumed by the solid caustic surface, generating a superficial sodium carbonate crust if CO₂ is present; this crust slows dissolution and alters alkalinity accounting. A typical charge is controlled to 1–5 kg/min per 500 L reactor using a loss-in-weight screw feeder with nitrogen purge. The solid is not added to hot reaction mass above 80 °C unless the reactor is designed for localised boiling. In alcoholic media, caustic flakes dissolve more slowly than in water; reaction mixtures containing methanol or ethanol require pre-dissolution to avoid sedimentation and hot-spot conversion of alcohol to alkoxide with attendant viscosity rise. In soap and detergent saponification, the flakes are dissolved into process water before addition to the fat charge; uncontrolled direct addition creates high-local alkali concentrations that can promote clumping and inconsistent saponification.
The dissolution rate depends on flake thickness, agitation power input, and liquor temperature. Thicker flakes from rotary drum flakers dissolve slower than microprills; however, the lamellar structure provides greater initial surface area than pelletised forms of equivalent mass when the flakes are not compacted. In a full-scale caustic makeup loop equipped with a 30 kW agitator and a 10 m³ tank, a 500 kg charge of flakes at 20 °C feed water can raise the solution temperature to approximately 70 °C within 20–30 min; published data for this specific tank geometry is limited. The heat release is not uniform because the local concentration at the liquid–solid interface approaches saturation. This transient supersaturation increases solution density and can create density stratification in unbaffled tanks. Bottom-entry agitators or recirculation loops minimise hot zones and accelerate incorporation. An online conductivity monitoring point placed after the recirculation pump provides a proxy signal for concentration; readings stabilise only after the final flake is fully dissolved. Batch-to-batch variation in flake thickness can shift dissolution time by an observable margin, so retain samples from each received lot and record time-to-stable conductivity during the first production batch.
The flakes are deliquescent; exposure to air results in surface solution formation and carbonation. In storage silos, high-humidity air and temperature fluctuations drive moisture migration into the flake bed, leading to bridging, ratholing, and formation of hard carbonate crusts on silo walls. Silos shall be closed, fitted with desiccant-type air vents or nitrogen blanketing, and constructed with steep cone angles not less than 70° from horizontal. Hoppers with outlet diameters below 200 mm are prone to bridging because the flake geometry interlocks under compaction. Rotary valves handling caustic flakes require abrasion-resistant clearances and nitrogen-purged seals. In screw conveying, open-trough conveyors are not acceptable; fully enclosed screw or tubular drag conveyors with dust extraction are specified. The material should not be stored in outdoor areas or in direct sun exposure because cyclic temperature changes accelerate caking in the lower layers. When caking occurs, the affected material should be discarded or re-screened; forced breaking of caked flakes into the dissolver can introduce oversized particles that pass to downstream pumps and cause impeller wear.
In wastewater neutralisation, Rayalaseema Caustic Soda Flakes are reconstituted to 20–25% w/w NaOH solution and dosed through metering pumps into acid waste streams. The solid is not applied directly to open neutralisation basins because localised high pH above 12 can precipitate metal hydroxides unevenly and generate excessive heat. The reconstituted solution is injected into a turbulent zone with pH-controlled pumping, and the dosing line is fitted with a check valve and pressure relief to prevent backflow of acidic effluent into the caustic header. Membrane-cell flake material is preferred for trace metal-sensitive wastewater treatment because the low iron residual reduces the formation of iron hydroxide sludge in the dosing tank. The flake form also reduces bulk storage volume relative to 50% w/w liquid caustic by eliminating water mass, but requires sufficient water supply and controlled dissolution capacity at the point of use.
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