propane-1,2-diol · 1,2-Propanediol · PG · CAS 57-55-6
Nami-Barqarar — the moisture-retaining workhorse of modern cosmetics. This colourless, viscous diol simultaneously humectifies, solubilises actives, and preserves formulas across Pakistan's full climate range — from Lahore's 47°C summer heat to Karachi's coastal humidity — delivering science-proven performance at 1–30% in virtually every cosmetic category.
24–36 months sealed, cool, dark · Indefinite if contamination-free · No oxidation risk · Seal tightly after each use
Introduction
The Workhorse of Modern Cosmetics
Propylene Glycol (PG) is the invisible facilitator behind the performance of thousands of cosmetic products worldwide. Present in luxury serums and everyday shampoos alike, it is a colourless, viscous diol whose two hydroxyl groups perform an extraordinary range of functions simultaneously: drawing atmospheric moisture into the stratum corneum, dissolving actives that water cannot solubilise alone, temporarily enhancing the skin's permeability to co-formulated ingredients, and stabilising the product itself against microbial challenge and freeze-thaw stress. The Cosmetic Ingredient Review (CIR) Expert Panel estimates PG is used in over 9,000 cosmetic formulation types registered with the US FDA's Voluntary Cosmetic Registration Program — a figure that reflects its irreplaceability in professional formulation. Even brands and formulas positioned as "natural" or "organic" routinely include PG-adjacent or PG-derived ingredients, reflecting the industry's consensus on its safety and functional value.
For Pakistani cosmetic formulators, PG addresses climate challenges that few other ingredients resolve as elegantly. In Lahore, where summer temperatures exceed 47°C and relative humidity can drop below 30%, PG's hygroscopic humectancy maintains product texture and prevents water-phase drying throughout the product's life. In Karachi's coastal heat (38°C with 80%+ RH), PG stabilises emulsions against separation and microbial challenge. Its freezing point of −60°C means formulas incorporating PG will not crystallise during cold storage or shipping — a practical benefit for products distributed across Pakistan's diverse climate zones. For Pakistan's most commercially significant skin concern — post-inflammatory hyperpigmentation (PIH) in Fitzpatrick Type III–V skin — PG at 10–20% as a penetration enhancer for actives such as Alpha Arbutin, Kojic Acid Dipalmitate, and Niacinamide may significantly improve clinical outcomes compared to equivalent PG-free formulas.
Bio Shop™ Pakistan — Sourcing Note
Bio Shop™ Pakistan stocks Propylene Glycol at Cosmetic / USP Grade (≥99.5% assay) — the pharmaceutical and cosmetic standard. Supplied as a clear, colourless, viscous liquid in sealed HDPE. Suitable for all topical cosmetic formulations: face creams, serums, lotions, shampoos, conditioners, gels, cleansers, toners, body washes, sunscreens, deodorants, and lip products. CoA available with batch documentation. Visit bioshop.pk/products/pg-propylene-glycol-liquid for current stock and pricing.
Molecular Identity
Chemical Identification
IUPAC Namepropane-1,2-diol
INCI NamePROPYLENE GLYCOL
CAS Number57-55-6
EINECS / EC200-338-0
CosIng Reference37269 — EU cosmetic ingredient database
Food AdditiveE 1520 — permitted food additive in EU, USA, and Pakistan
Synthesis RoutePetrochemical: hydration of propylene oxide (from propylene) at 130–200°C, 2 MPa · Bio-based: catalytic hydrogenolysis of glycerol (biodiesel by-product) · Both routes produce identical molecule
PharmacopoeialUSP, PhEur, BP grade available — identical chemistry to cosmetic grade
Urdu / PakistanNami-Barqarar (نمی برقرار) — Moisture Retainer · Technical cosmetic term; widely used in professional Pakistani formulation
Grade & Purity Profiles
Four Commercial Grades
Propylene Glycol is commercially available in grades ranging from industrial to pharmaceutical. Only Cosmetic / USP Grade should ever be used in topical or personal care applications. Bio Shop™ Pakistan stocks the Cosmetic / USP Grade (≥99.5% assay) — the same specification required by international cosmetic and pharmaceutical manufacturers. Pakistan's grey market occasionally introduces industrial-grade material relabelled as cosmetic grade; always verify through Certificate of Analysis.
Bio Shop™ Grade · Professional Standard
Cosmetic / USP Grade
≥99.5% assay · APHA ≤10 · Sp. Gr. 1.032–1.040 · DEG/EG ≤0.1% each
Assay Purity
≥99.5%
Heavy metals ≤10 ppm · RI 1.431–1.433 · pH 6.0–7.5
"The only grade suitable for skin, hair, and personal care applications. Meets USP, PhEur, and BP standards. Bio Shop™ Pakistan primary stock. CoA with batch-specific assay, density, APHA, and DEG/EG levels available on request. Suitable for all topical product categories."
Required for injectable drugs — not necessary for cosmetics
"The highest purity tier, designed for parenteral pharmaceutical applications (IV fluids, injections). Chemically identical to cosmetic grade but with sterility and endotoxin testing. Over-specified and significantly more expensive for cosmetic use. Cosmetic / USP grade is entirely sufficient for all topical products."
Bio-Based · Sustainability Claim
Bio-Based / Plant-Derived
Glycerol hydrogenolysis route · Renewable carbon · 10–20% cost premium · Same CAS 57-55-6
Assay Purity
≥99.5%
Molecularly identical; "plant-derived" or "bio-based" label claim possible
"Produced by catalytic hydrogenolysis of glycerol (biodiesel by-product). Enables 'bio-based', 'plant-derived', or 'sustainable' label claims for EU-export clean beauty brands. Olfactorily and functionally identical to petrochemical grade. For Pakistani domestic market and standard cosmetics, petrochemical USP grade is recommended for cost efficiency."
⚠ Never Use in Cosmetics
Industrial Grade
Pakistan grey market · High DEG/EG · Catalytic residues · Unverified heavy metals
Actual Purity
<99%
Used in antifreeze, heat transfer, industrial solvents ONLY
"Designed for antifreeze, plastics, and industrial chemical processing. May contain elevated diethylene glycol (DEG), ethylene glycol (EG), catalytic residues, and heavy metals above cosmetic limits. NEVER use industrial grade in any topical, hair, or personal care formulation. Verify via CoA: assay ≥99.5%, APHA ≤10, Sp. Gr. 1.032–1.040."
Dosage Science
Concentration Behaviour
Propylene Glycol is unique among cosmetic ingredients in that its primary function changes with concentration: below 5% it acts mainly as a solvent and stabiliser; at 5–10% meaningful humectancy emerges; at 10–20% penetration enhancement becomes clinically significant for co-formulated actives; above 20% antimicrobial activity and powerful solvency dominate. The CIR Expert Panel has confirmed PG safe at up to 50% in cosmetics, but practical formulation guidelines identify 1–20% as the optimal range for leave-on products in the Pakistani market. South Asian skin types III–V benefit particularly from the 10–20% range, where PG-enhanced delivery of brightening actives (arbutin, kojic acid, niacinamide) provides clinically superior outcomes compared to PG-free aqueous bases.
<2% in FormulationSolvent & Stabiliser
Primarily a co-solvent for preservatives, emulsifiers, and fragrance — provides minimal direct skin benefit at this level. Improves freeze-thaw stability of the aqueous phase; increases preservation efficacy. Ideal for body washes, shampoos, and deodorants seeking formulation stability
2–5% in FormulationMild Humectancy
Mild humectancy improving skin feel and spreadability; improves texture of lightweight products. Suitable for oily and acne-prone Karachi skin that benefits from lightweight hydration without oil loading; toners, cleansers, serums with low active load
5–10% in FormulationSignificant Humectancy
Clinically measurable TEWL reduction; smooth skin feel; initial penetration enhancement. Standard range for face creams, body lotions, hair conditioners, and shampoo bases. Excellent for Lahore dry-heat applications where stratum corneum water retention is the primary formulation goal
10–20% in FormulationActive Delivery Zone
Strong humectancy plus meaningful penetration enhancement for co-actives; mild antimicrobial synergy. The sweet spot for treatment serums with brightening actives targeting Pakistani hyperpigmentation. PG at 15% significantly enhances delivery of Alpha Arbutin, Kojic Acid Dipalmitate, and Niacinamide to melanocyte layer
20–30% in FormulationSpecialised Treatment
Very strong solvent and penetration enhancer; antimicrobial activity significant; potentially drying on sensitive skin without occlusives in low-humidity environments. Suitable for scalp serums, peel preparations, hair treatment products with professional use. Ensure formula includes sufficient occlusives to prevent net TEWL increase
Above 30% in FormulationSolvent-Dominant
Not recommended for full-face leave-on products on general consumer skin; increasing irritation risk for sensitive or compromised barrier. Suitable for restricted-area treatment serums, pharmaceutical topicals. CIR confirms safe up to 50%, but below 30% covers all standard cosmetic applications. Rinse-off products tolerate higher levels better than leave-on
Mechanism of Action
Functional Performance Profile
Primary Function · Mechanism 1
Humectant Action
Propylene Glycol's two hydroxyl groups form hydrogen bonds with water molecules, drawing atmospheric moisture into the stratum corneum and binding it there against evaporative loss. This is the mechanism underlying its primary commercial value. Corneometer measurements confirm statistically significant increases in stratum corneum water content within 15–30 minutes of application. In Pakistan's dual climate extremes — Lahore's low-humidity summer (RH <30%) and Karachi's coastal humidity (RH 75–85%) — PG performs reliably in both conditions: in dry Lahore air, it redistributes moisture from deeper skin layers upward into the stratum corneum; in humid Karachi air, it attracts atmospheric moisture. For maximum effect, always co-formulate with an occlusive (shea butter, beeswax, petrolatum) to prevent PG-attracted moisture from re-evaporating in dry climates. Without occlusives, a PG-only serum can theoretically increase net TEWL in very dry conditions (RH <30%).
Secondary Function · Mechanism 2
Penetration Enhancement
At concentrations above approximately 10%, PG intercalates into the lamellar lipid bilayers of the stratum corneum, temporarily increasing lipid fluidity and disorder. This reversible modification of the skin barrier enhances the permeability of co-formulated active ingredients — including Alpha Arbutin, Kojic Acid Dipalmitate, Niacinamide, Allantoin, and Panthenol — allowing them to reach their target sites in the viable epidermis more efficiently. SAXD and FTIR studies confirm this mechanism at molecular level. For Pakistani formulators addressing PIH (post-inflammatory hyperpigmentation), the most commercially significant concern in Fitzpatrick III–V skin, PG at 15–20% as a delivery vehicle for brightening actives offers a meaningful clinical advantage over PG-free aqueous bases. The penetration-enhancing effect is fully reversible: within a few hours of PG dissipating from the skin surface, the lamellar lipid structure returns to baseline without permanent barrier alteration.
Tertiary Function · Mechanism 3
Solvency & Stabilisation
PG's combination of high polarity, water-miscibility, and partial lipophilic character (log Pow −0.92) makes it an outstanding co-solvent for cosmetic actives that are poorly soluble in water alone. It solubilises: vitamin derivatives (Niacinamide, Panthenol, SAP), botanical extracts, preservatives (Phenoxyethanol, Parabens), fragrance components, and some lipophilic actives. As a viscosity modifier, PG reduces the viscosity of Carbomer gels by approximately 10–20% at 10–20% use levels — compensate by increasing Carbomer concentration 0.05–0.1%. Its freeze-thaw stabilisation function is practically relevant for Pakistani products distributed through warehouses without temperature control: PG's freezing point of −60°C prevents aqueous phase crystallisation during cold storage cycles, maintaining emulsion integrity from the factory to the consumer's bathroom across Pakistan's full temperature range (Murree −10°C to Jacobabad 48°C).
Quaternary Function · Mechanism 4
Preservation Boost
At levels above 15%, Propylene Glycol inhibits the growth of bacteria and fungi through a combination of water activity reduction and direct membrane-disruption mechanisms. This antimicrobial contribution provides meaningful secondary preservation support — not a standalone preservative, but a synergistic booster that allows reduction of primary preservative use levels. Particularly valuable in Pakistani formulation context: Lahore and Karachi warehouse temperatures of 35–45°C during summer significantly accelerate microbial challenge to cosmetic products stored outside air-conditioned facilities. PG at 15% combined with Sodium Benzoate 0.2% + Potassium Sorbate 0.2% forms a complete, halal-compatible, heat-stable broad-spectrum preservation system that is well-proven in tropical climate markets. PG also reduces water activity (aw) in the aqueous phase, further contributing to microbial inhibition at high concentrations.
Three production-ready formulas from the Bio Shop™ Pakistan reference document — exact weights, exact percentages. All ingredients available at bioshop.pk where confirmed. Formula 1 is a rinse-off brightening ubtan-gel mask. Formula 2 is a K-beauty-inspired leave-on brightening water serum. Formula 3 is a deep conditioning hair mask targeting South Asian hair profiles.
Noor-e-Rung Ubtan Gel · نور رنگ ابثن
Rinse-off Brightening Clay Mask · Traditional-Modern Hybrid · 100g batch · 50g jar · Pakistani women 20–45
► Disperse Xanthan Gum into warm water (50°C) with vigorous mixing; hydrate 20 min. ► Combine PG, glycerin, Alpha Arbutin, Niacinamide, Allantoin; mix until dissolved. ► Add Phase A solution to xanthan gel. ► Slowly blend Phase B clays by sifting to avoid lumps. ► Cool to below 40°C; add Germall Plus. ► Add rose water to reach 100%. ► Adjust pH to 5.2–5.8 with Citric Acid solution. ► Package into 50–75g jars. Use-time: 15–20 min; rinse off. Shelf life: 12–18 months sealed.
Noor-e-Rung Serum · نور رنگ سیرم
Brightening Water Serum · K-Beauty Inspired · Leave-on · 100g compound · Urban Pakistani women 20–40
⚠ Formula correction: Source document lists Distilled Water at 54.4% but the ingredient sub-totals require 61.4% water for a 100g batch. Water adjusted to 61.4% accordingly.
► Disperse HA Powder into warm water; stir until dissolved. ► Add PG, glycerin, Sodium PCA; mix. ► Dissolve Niacinamide, Alpha Arbutin, SAP in Phase A at 50°C max. ► Cool to 40°C; add xanthan gum pre-dispersed in PG. ► Below 40°C: add phenoxyethanol, ethylhexylglycerin, allantoin, ferulic acid (pre-dissolved in PG), rosemary extract. ► Adjust pH to 5.5–6.0 with Citric Acid. Preservation: Phenoxyethanol 0.8% + Ethylhexylglycerin 0.2% + PG 20% (booster). Shelf life: 18–24 months sealed.
Zulfon ki Taraawat · زلفوں کی تراوت
Intensive Deep Conditioning Hair Mask · Leave-on 15–20 min then rinse · 100g batch · South Asian hair · All Pakistan regions
⚠ Formula correction: Source document lists Distilled Water at 48.8% but ingredient sub-totals require 59.0% water for a 100g batch. Water adjusted to 59.0% accordingly.
Fragrance / Rose EO — optional (dissolve in PG first)0.50g 0.5%
Method
► Heat Phase A water to 70°C; dissolve PG, glycerin; set aside. ► Melt Phase B (BTMS 85, cetyl alcohol, shea butter) at 70°C; add argan oil, dimethicone. ► Slowly pour Phase B into Phase A with continuous mixing; emulsify 3–5 min. ► Mix in keratin, panthenol, silk protein, aloe at 60°C. ► Cool to 40°C with slow mixing. ► Below 40°C: add Germall Plus, fragrance (pre-dissolved in PG). ► Adjust pH to 4.5–5.0 with Citric Acid. ► Fill into 200g jars. Apply 15–20 min before shower; rinse thoroughly. Shelf life: 18–24 months sealed.
Synergies
Classic Pairings
Propylene Glycol is chemically compatible with virtually all standard cosmetic ingredients. The following pairings represent the most commercially successful and scientifically validated combinations for Pakistani formulation, drawn from the source reference document. Each combination exploits a specific functional synergy.
Stronger humectant per gram (3 −OH groups vs 2); heavier, more viscous skin feel; less solvent power; minimal penetration enhancement; no freeze-thaw benefit
EU / DRAP Status
✓ EU Permitted · No restriction · DRAP Pakistan: no restriction · CIR confirmed safe · Universally accepted
Use With PG
Standard duo: PG 10% + Glycerin 3–5% covers Lahore (dry) and Karachi (humid) humidity ranges simultaneously — complementary, not competitive
Pakistan Application
Best combined with PG in all standard moisturisers; use glycerin alone when PG-free labelling is a consumer-facing requirement
Verdict: The natural first partner for PG in Pakistani formulation. Glycerin provides stronger surface humectancy; PG provides deeper penetration enhancement and solvency. Always combine rather than choosing one. Glycerin — verify bioshop.pk availability with supplier.
1,3-Propanediol
1,3-Diol · Bio-fermented · MW 76.09 g/mol · CAS 504-63-2
Function vs. PG
Similar humectancy; slightly lighter, less sticky skin feel; marginally different solvent characteristics (OH groups at 1,3 vs 1,2 positions); bio-fermented route available for natural claims
EU / DRAP Status
✓ EU Permitted · No restriction · Available at bioshop.pk/products/propanediol · 10–20% price premium vs PG
Use With PG
Direct substitute when 'PG-free' or 'natural' consumer positioning is required; not typically blended with PG as functions are similar
Pakistan Application
Growing in demand for export-oriented clean beauty products; domestic consumers not yet differentiating; PG remains the cost-effective choice for standard formulation
Verdict: The preferred PG substitute for clean beauty positioning. Functionally similar at standard use levels (2–8%), with the advantage of bio-based origin and slightly more modern skin feel. Available at bioshop.pk/products/propanediol.
Hyaluronic Acid Powder
Polysaccharide · High MW film-former · 0.01–1% use level
Function vs. PG
Complementary, not competitive — HA forms a hygroscopic film on the skin surface; PG penetrates into the stratum corneum. Different depth of action; different use levels; different price points
EU / DRAP Status
✓ EU Permitted · No restriction · Available at bioshop.pk/products/hyaluronic-acid-powder · Higher cost per gram than PG
Use With PG
Standard premium serum system: PG 15% (SC penetration + humectancy) + HA 0.5% (surface film + plumping marketing story) = Full-spectrum hydration
Pakistan Application
'HA Serum' is one of the highest-demand categories in urban Pakistani beauty (Karachi, Lahore); PG 15% + HA 0.5% provides the clinical efficacy and the premium positioning story simultaneously
Verdict: Always use together, never as alternatives. HA provides the premium ingredient story and surface moisture film; PG provides the actual penetration, delivery, and preservation functionality. Together they create the most commercially compelling hydration serum for Pakistan.
Natural Moisturising Factor (NMF) component naturally found in skin; excellent stratum corneum affinity; more potent humectant per gram but much lower use level (0.5–2%); no solvent or penetration-enhancement function
EU / DRAP Status
✓ EU Permitted · No restriction · Available at bioshop.pk/products/sodium-pca-pyrrolidone-carboxylic-acid · Higher cost per gram
Use With PG
Optimal humectant stack for Pakistani climate: PG 10% + Glycerin 3% + Sodium PCA 1% = broad-spectrum hygroscopic system covering both Lahore dry heat and Karachi humidity
Pakistan Application
Adds 'skin-identical' and 'natural moisturising factor' label claims at low cost addition; excellent for premium serum positioning targeting educated urban consumers in Lahore and Karachi
Verdict: Excellent complementary humectant at low use levels. Adds NMF credentials without replacing PG's solvency, penetration-enhancement, or preservation-booster functions. Budget the difference (lower Sodium PCA volume vs higher cost) accordingly.
Safety & Regulations
EU Cosmetics & Safety Overview
Educational summary of publicly available regulatory data as of 2024–2025. Always consult the current EU Cosmetics Regulation (EC) No 1223/2009, FDA guidelines, and the ingredient SDS before commercial formulation. Pakistani formulators should review applicable DRAP cosmetic notifications. This document does not constitute regulatory, safety, legal, or medical advice.
✓
EU Cosmetics Regulation 1223/2009 — Freely Permitted
Propylene Glycol is freely permitted in cosmetic products under EU Regulation (EC) No 1223/2009. It does not appear in Annex II (Prohibited), Annex III (Restricted), Annex IV (Colorants), Annex V (Preservatives), or Annex VI (UV Filters). No quantitative upper limit is imposed. The CIR Expert Panel has confirmed PG safe at concentrations up to 50% in cosmetics. For EU-export Pakistani products, no allergen labelling requirement applies to PG under Regulation 2023/1545 (which targets fragrance allergens only). CosIng database confirms PG status as unrestricted permitted ingredient.
✓
FDA (USA) & DRAP Pakistan — Both Unrestricted
The US FDA classifies Propylene Glycol as GRAS (Generally Recognised As Safe) as a direct food additive under 21 CFR 184.1666 — one of the most comprehensive safety endorsements possible, as GRAS status implies safety even for ingestion at regulatory levels. Cosmetic use is freely permitted without restriction. Pakistan's Drug Regulatory Authority (DRAP) imposes no specific restriction on PG in cosmetic preparations. Pakistani formulators may use PG at any technically appropriate concentration in domestic formulations without regulatory concern.
✓
Halal Status — Confirmed by Major Certification Bodies
Cosmetic-grade PG is classified as Halal by JAKIM (Malaysia), IFANCA (USA), HFA (UK), and the Pakistan Halal Authority. The basis: (1) petrochemical grade is produced entirely from petroleum-derived propylene oxide with no animal inputs, no ethanol, and no fermentation-derived substances; (2) bio-based grade uses glycerol from plant-derived biodiesel with hydrogen gas and metal catalysts — also no animal inputs; (3) Islamic jurisprudence applied by Pakistani scholars confirms synthetic organic chemicals derived from non-prohibited raw materials are Halal for external cosmetic use. Bio Shop™ Pakistan can provide Halal compatibility documentation on request.
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Human Safety Profile — CIR Expert Panel Review
Acute oral LD₅₀ in rats >20,000 mg/kg (practically non-toxic by oral route — one of the highest safety margins in ingredient toxicology). CIR reviews (1994, 2012) consistently affirm PG safe at up to 50% in cosmetics. Negative in Ames test; no carcinogenicity in lifetime rodent studies; not classified as reproductive toxicant. Sensitisation risk: estimated 0.8–3.5% of patch-tested dermatology patients, predominantly in atopic dermatitis with compromised barrier. General population rate is significantly lower. At typical cosmetic leave-on levels (5–15%), sensitisation risk is low. For sensitive or atopic skin, keep below 5%; consider substituting with 1,3-propanediol or glycerin.
⚠️
Sensitive Skin & Special Populations
PG should be used with care in: (1) individuals with confirmed PG contact allergy — substitute with 1,3-propanediol or glycerin; (2) products for atopic dermatitis patients, where compromised barrier increases irritation risk above 5%; (3) infants and children — immature skin barrier; keep levels to 1–3%; (4) occluded application areas where higher effective concentrations may cause irritation; (5) pregnant or nursing women — systemic absorption from normal cosmetic use is minimal but formulators should use conservative levels (≤10% leave-on). For full-body leave-on formulas above 30%, assess safety professionally before commercial release.
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Environmental — Readily Biodegradable
Propylene Glycol is readily biodegradable and has low environmental persistence. Unlike some polyols, PG does not bioaccumulate. OECD biodegradability tests confirm >90% mineralisation within standard test periods. At typical consumer product usage levels, real-world environmental load is negligible. In Pakistan's major cities (Lahore, Karachi) where urban waterway quality is an environmental concern, PG does not represent a priority environmental risk compared to surfactants and preservatives in the same formulas. Dispose of bulk waste concentrate diluted before drain — avoid concentrated disposal into waterways. No special environmental handling requirements for consumer product use levels.
Handling & Storage
Storing in Pakistan's Climate
Temperature Stability
Chemically stable across all Pakistani temperature ranges (5–47°C). Freezing point −60°C — will never freeze in Pakistani conditions. Boiling point 188°C — no vapour loss risk at storage. No cooling required; standard warehouse storage acceptable
Container Type
Sealed HDPE drums or carboys · Stainless steel IBC for large quantities · Glass or PET for lab quantities · AVOID aluminium (PG slowly attacks aluminium over long periods) · AVOID PVC for long-term storage
Light Exposure
PG is NOT photosensitive. UV/light exposure has minimal impact on chemical integrity. Standard opaque HDPE or drum storage is acceptable. No amber glass or UV-blocking packaging required — a significant advantage over light-sensitive actives
Shelf Life
24–36 months in sealed containers; effectively indefinite if contamination-free (no oxidation risk unlike oils). Once opened: 12–18 months with proper sealing. Key risk is contamination, not chemical degradation. Check for unusual odour or colour before use
Lahore Summer (May–Aug)
Temperatures 38–47°C — PG remains chemically stable. No active cooling required for raw PG storage. For formulas containing PG: ensure finished product is tested at 40°C/75% RH accelerated stability before release. Standard non-temperature-controlled warehouse storage acceptable for bulk PG
Karachi Coastal Climate
High humidity 60–85% RH year-round is the key concern: PG is strongly hygroscopic and will absorb atmospheric moisture from an open container, causing dilution and density drop. ALWAYS seal immediately after each use. Use desiccant packets in storage area. Check density periodically if container has been repeatedly opened. Diluted PG — lower density and RI — indicates moisture absorption
Measuring Technique
PG is liquid at all Pakistani temperatures — easy to measure by weight. Use 0.01g precision balance for formulation batches. At high use levels (10–20%), standard 0.01g balance is sufficient. For trace-level solvent applications: measure by volume using calibrated glass pipette or measure by weight (Sp. Gr. 1.035 at 20°C)
Cross-Contamination Risk
PG's solvent power means it can absorb odours and trace chemicals from surrounding environment. Store away from strongly scented materials, reactive chemicals, and open fragrance containers. A contaminated batch of PG will off-note any formula it enters. Perform organoleptic check before use: odourless or faint sweet — acceptable; any off-note — investigate before using
⚠ Adulteration check: Genuine Cosmetic/USP Grade PG (CAS 57-55-6) is a clear, colourless, viscous liquid. Density: 1.032–1.040 g/cm³ at 20°C (weigh 1.00 mL — should be 1.032–1.040g). Below 1.025 = water dilution or substitution. Refractive Index: 1.431–1.433 at 20°C (glycerol adulterant gives RI ~1.471 — distinctly different). Viscosity feel: noticeably more viscous than water but much thinner than glycerol. Thin, water-like consistency = diluted. Always request CoA with assay, APHA, Sp. Gr., DEG, EG from supplier.
FAQs
Frequently Asked Questions
Is Propylene Glycol Halal? What is its exact synthesis origin?+
Propylene Glycol used in cosmetic-grade formulations is classified as Halal by JAKIM, IFANCA, HFA, and the Pakistan Halal Authority. The evidence: (1) The predominant industrial route is hydration of propylene oxide at 130–200°C, 2 MPa. Propylene oxide is derived from propylene — a petroleum refinery by-product. No animal-derived materials, ethanol, or fermentation-derived substances are involved at any stage. (2) The bio-based route uses glycerol (a by-product of plant-derived biodiesel manufacturing) under hydrogen gas with metal catalysts (copper chromite or noble metals) at 180–220°C. Also fully free of animal inputs. (3) Both synthesis routes yield chemically identical 1,2-propanediol (CAS 57-55-6) with no animal-origin residue. (4) Islamic jurisprudence applied by Pakistani scholars confirms synthetic organic chemicals derived from non-prohibited raw materials, used externally in cosmetics, are Halal. Bio Shop™ Pakistan can provide Halal compatibility documentation from the manufacturer upon request for professional accounts.
How do I verify PG purity when buying in Pakistan? What adulterations are common?+
Always request a batch-specific Certificate of Analysis (CoA) confirming assay ≥99.5%, APHA ≤10, and specific gravity 1.032–1.040 at 20°C. Three practical verification tests available without GC equipment: (1) Density test: weigh 1.00 mL on a 0.001g balance — pure PG should read 1.032–1.040g per mL. Below 1.025 indicates water dilution or substitution with a less dense compound. (2) Refractive Index test: pure PG gives RI 1.431–1.433 at 20°C. Glycerol adulterant gives RI ~1.471 — clearly different on any Abbe refractometer available at university labs in Lahore or Karachi. (3) Viscosity feel: pure PG at room temperature is noticeably more viscous than water but much thinner than glycerol. If your sample feels as thin as water, it has been diluted. Common grey-market adulterations: industrial-grade PG (higher DEG/EG impurities), glycerol-PG blends (identifiable by higher density and RI), and water-diluted PG. Bio Shop™ Pakistan stocks verified cosmetic/USP grade with CoA documentation.
How should I store Propylene Glycol in Pakistan's hot and humid climate?+
Propylene Glycol is one of the most climate-stable raw materials available to Pakistani formulators — far more tolerant of temperature and humidity extremes than botanical extracts, oxidation-prone oils, or light-sensitive actives. In Lahore (5–47°C seasonal range): chemically stable at all temperatures; no cooling required; no UV degradation risk; standard HDPE drum storage is fully adequate. The only precaution: avoid aluminium containers, as PG slowly reacts with aluminium over long periods. In Karachi (60–85% RH year-round): the single meaningful concern is PG's hygroscopicity. Always seal containers immediately after each use. Use desiccant packets in storage drawers or cabinets. In a high-humidity Karachi workshop, an unsealed 5L container of PG can absorb meaningful amounts of atmospheric moisture within days, diluting it below USP specification. Periodically verify density if the container has been repeatedly opened. Shelf life: 24–36 months sealed; 12–18 months once opened with proper resealing discipline.
What is the correct use level for PG in cosmetics? Can I use more than 20%?+
Yes, PG can be used above 20% safely. The CIR Expert Panel confirmed PG safe at concentrations up to 50% in cosmetic formulations — one of the highest approved ceilings for any cosmetic ingredient. However, practical guidelines for Pakistani formulators suggest: below 2% for solvency and stabilisation only; 2–5% for mild humectancy and skin feel improvement; 5–10% for meaningful humectancy in standard moisturisers and conditioners; 10–20% for active delivery enhancement in brightening serums, treatment products, and hair therapies targeting South Asian hair; 20–30% for specialised treatment products where solvent power and penetration enhancement are the primary goals. Above 15% under occlusion on sensitive skin, some individuals may experience mild irritation. For full-face leave-on products, 10–20% is the sweet spot for efficacy, comfort, and safety in Pakistan's Fitzpatrick III–V skin profile. There is no regulatory maximum for PG in cosmetics in Pakistan, EU, or USA.
Is PG safe for Pakistani skin types? Any hyperpigmentation or photosensitivity risk?+
Propylene Glycol does not cause hyperpigmentation and is not phototoxic (confirmed by standard OECD phototoxicity testing). For Pakistani skin types III–V — which are more prone to post-inflammatory hyperpigmentation (PIH) from irritation — the key safety rule is to keep PG below the irritation threshold: generally below 15% in leave-on products on normal skin, and below 5% for confirmed sensitive or atopic skin. At these levels, PG is non-irritating for the vast majority of users and in fact serves as a beneficial delivery vehicle for anti-PIH actives (arbutin, niacinamide, kojic acid). The only genuine skin safety concern is contact sensitisation, estimated at 0.8–3.5% of patch-tested dermatology patients (general population rate is significantly lower). For any consumer reporting persistent itching or redness after PG-containing products, a patch test is advisable and alternatives (1,3-propanediol or glycerin) are appropriate substitutes.
Can I use PG with Vitamin C, acids, niacinamide, and other actives? What should NOT be combined?+
Propylene Glycol is broadly compatible with virtually all standard cosmetic actives and performs as an excellent delivery vehicle for many. Compatible pairings (all confirmed stable): Niacinamide 5–10% (PG solubilises and delivers to melanocytes; stable at pH 5.5–6.5); Alpha Arbutin 1–3% (PG enhances penetration to tyrosinase sites); SAP and MAP (stable Vitamin C derivatives; PG maintains stability at pH 5.5–6.0); AHAs (glycolic, lactic, mandelic at pH 3.5–4.5); BHA Salicylic Acid ≤2% at pH 3–4; Allantoin; Panthenol; Hyaluronic Acid; and most botanical extracts. Handle with care: L-Ascorbic Acid — keep formulas strictly at pH 2.5–3.5 for stability; Retinol — stable in PG at pH 6–7 but PG may slightly enhance retinol delivery, so start at 0.05% and assess irritation before increasing. No strict chemical incompatibilities exist for PG with common cosmetic ingredients, but always match pH to active requirements.
Which Pakistani consumer segments and product formats work best with Propylene Glycol?+
Four Pakistani consumer segments show the strongest commercial response to PG-containing products. First, urban women 20–40 with hyperpigmentation and PIH concerns (Karachi, Lahore, Islamabad) — the largest and most commercially active cosmetic segment in Pakistan; PG at 15–20% as a delivery vehicle for brightening actives directly addresses their primary concern. Second, Lahore dry-heat consumers seeking all-season moisturisers — PG 10–15% in cream base provides lasting humectancy across the extreme climate range. Third, Karachi oily and combination skin consumers — PG 3–5% in lightweight gel-serum format provides hydration without adding oiliness in humid conditions. Fourth, Pakistani women 25–45 with dry, frizzy, or damaged South Asian hair — PG 8–10% in BTMS-based conditioning masks significantly improves manageability and reduces frizz in one to two applications. Best-performing product formats: lightweight gel-serum (Karachi oily skin), cream/lotion (Lahore dry skin), deep conditioning mask (all regions), and toner/essence (growing urban 18–35 segment).
What Urdu brand names work for PG-based products? How does it perform in Pakistan's summer heat?+
Recommended Urdu and bilingual brand/product naming vocabulary for PG-featuring formulas: Nami-Barqarar (نمی برقرار) — Moisture Retainer, ideal for moisturiser branding; Noor-e-Rung (نور رنگ) — Light of Complexion, perfect for brightening serum; Bahar-e-Nami (بہار نمی) — Spring of Moisture, for gel-cream; Zulfon ki Taraawat (زلفوں کی تراوت) — Freshness of Hair, for conditioning mask; Raushan Asaar (روشن آثار) — Illuminating Effects, for a premium brightening range. Pakistan summer heat performance: PG is genuinely climate-adaptive in hot conditions. In Lahore at 42–47°C, higher skin temperature does not degrade PG's humectant function — if anything, the elevated temperature improves its penetration-enhancing effect, as warmer SC lipids are more amenable to PG intercalation. Unlike fragrance ingredients that evaporate in heat, PG (BP 188°C) remains entirely in the formula. The key formulation consideration for summer in Pakistan: always include occlusives in leave-on formulas to prevent PG-attracted moisture from re-evaporating in dry summer air (Lahore RH drops below 20% in May–June).
Everything on this page and substantially more — complete molecular structure-activity relationship analysis for PG's two hydroxyl groups and the skin science behind each function, full SAXD and FTIR evidence for stratum corneum lipid intercalation, complete CIR Expert Panel safety assessment data (1994 and 2012), detailed comparison of petrochemical vs bio-based synthesis routes with isotopic verification methods, Pakistan-specific market analysis with three product concepts (Noor-e-Rung Clay Mask, Noor-e-Rung Brightening Serum, Zulfon ki Taraawat Hair Mask), full accelerated stability testing protocols for Pakistan climate conditions, advanced formulation strategies for 15+ product categories, and a comprehensive 20-term glossary of cosmetic chemistry and skin science — all in one professional reference document.
