Specifications

Complete specifications for PTFE watch glasses. Items marked Customizable are available upon request.

Diameter (mm)	Capacity Ref. (ml)	Fits Beaker Size	Height (mm)	Status
50	~11	50ml	—	Customizable
60	—	50-100ml	—	Standard
70	—	100ml	—	Standard
75	~21	100-150ml	—	Customizable
80	—	150-200ml	—	Standard
90	—	200-250ml	—	Standard
100	~33	250-400ml	—	Standard
120	—	500-600ml	—	Standard
125	~86	600-1000ml	—	Customizable
150	~237	1000-2000ml	—	Standard
180	—	2000ml+	—	Standard

Height may vary slightly by manufacturer — check the actual product.

📌 Customization Notes:
• Material Upgrade: PFA (translucent, visible contents, lower metal leaching)
• Thickness: Standard 2-4mm — thicker/thinner options available upon request
• Custom Sizes: Non-standard dimensions available — consult our technical team

Product Description

I. Overview

The PTFE watch glass is manufactured from high-purity PTFE resin through precision cold pressing and high-temperature sintering. With an extremely low surface energy of 18.5 mN/m — the lowest among known solid materials — PTFE offers exceptional non-stick properties, minimal sample residue, and effortless cleaning.

Compared to traditional glass watch glasses, PTFE offers overwhelming chemical resistance — compatible with hydrofluoric acid, aqua regia, concentrated sulfuric and nitric acids, and virtually all aggressive reagents. It maintains stable performance across a wide temperature range from -196℃ to 260℃, suitable for both liquid nitrogen environments and high-temperature ovens.

Available in eight diameters from 60mm to 180mm to fit various container sizes. Widely used in pharmaceutical, semiconductor, environmental testing, and materials science laboratories.

II. Core Performance Parameters

Purity: High-purity PTFE with ultra-low metal leaching (Pb, U < 0.01ppb)
Operating Temperature: -196℃ ~ 260℃, short-term up to 300℃
Surface Energy: 18.5 mN/m (lowest among solid materials)
Friction Coefficient: 0.04 ~ 0.10 (extremely low, non-adhesive)
Chemical Resistance: Resistant to HF, aqua regia, concentrated H₂SO₄, HNO₃, strong alkalis, and organic solvents
Sterilization: Autoclavable (121℃, 2bar) or dry heat sterilization

III. Material & Workmanship

Manufactured from imported high-purity PTFE resin, cold-pressed in precision molds, and processed through gradient sintering in cleanroom environments — ensuring a dense, bubble-free structure with a smooth, uniform surface. Each product undergoes rigorous visual and dimensional inspection.

PTFE watch glasses are translucent white with smooth, rounded edges — no burrs that could scratch benchtops or damage container walls. Lightweight yet durable for long-term repeated use.

Applications

Typical Applications

Solution Concentration

Place sample solution on the watch glass and evaporate in a water bath or oven — ideal for trace sample pre-concentration

Crystallization

Slow solvent evaporation on the watch glass for crystal growth in chemical, pharmaceutical, and materials science research

Dust Protection

Cover beakers, dishes, and other containers to prevent airborne particle contamination while allowing gas exchange

Corrosive Sample Storage

Temporary storage of strong acids, bases, and organic solvents — PTFE ensures zero corrosion risk

Weighing Boat

Use as a weighing dish for powders and granular samples

Electron Microscopy Sample Prep

Sample dispersion and drying on the watch glass surface

Industries

Pharmaceutical Drug crystallization, solution concentration, stability testing
Semiconductor Wafer surface treatment, photoresist preparation, chemical storage
Environmental Testing Water sample pretreatment, soil extract concentration
Materials Science Nanomaterial dispersion, thin film preparation
Research Institutes General laboratory operations

Chemical	PTFE Compatibility	Recommended Temperature	Notes
Hydrofluoric Acid (HF)	✅ Fully Compatible	≤ 250℃	PTFE is the only reliable material
Aqua Regia	✅ Fully Compatible	≤ 200℃	Avoid evaporating to dryness at high temperature
Conc. H₂SO₄ (98%)	✅ Fully Compatible	≤ 250℃	Handle with care when heating
Conc. HNO₃ (65%)	✅ Fully Compatible	≤ 250℃	Store away from light
NaOH (50%)	✅ Fully Compatible	≤ 200℃	Safe handling required for concentrated alkalis
Organic Solvents	✅ Fully Compatible	≤ Solvent BP	Ensure ventilation and fire safety

Selection Guide

I. By Application

Application	Recommended Diameter	Recommended Material	Notes
Micro-volume concentration	60-80mm	PTFE (standard) / PFA (high-purity)	For small sample volumes
Routine crystallization	90-120mm	PTFE	Moderate coverage area
Large volume processing	150-180mm	PTFE	For large beakers
Corrosive sample storage	100-150mm	PTFE	Chemical resistance is key
Ultra-trace analysis	80-120mm	PFA	Ultra-low metal leaching

II. By Vessel Compatibility

50ml beakers: Recommend 50-60mm watch glass
100-250ml beakers: Recommend 70-90mm watch glass
250-500ml beakers: Recommend 100-120mm watch glass
600-1000ml beakers: Recommend 125-150mm watch glass
2000ml+ beakers: Recommend 150-180mm watch glass

III. Material Selection

PTFE (standard): Cost-effective, suitable for most corrosive operations
PFA (upgrade): Translucent for content visibility, lower metal leaching — ideal for ultra-trace analysis

💡 Selection Tip: Choose a watch glass diameter slightly larger than your vessel's mouth to ensure complete coverage. For evaporation/concentration, select a diameter 10-20mm larger than the vessel opening to provide sufficient surface area and working margin. For ultra-trace analysis (ICP-MS level), choose PFA material to minimize metal leaching risks.

Operation & Maintenance

User Guide

Standard operating guidelines for PTFE watch glasses. Proper use and maintenance significantly extend product life and ensure laboratory safety.

I. Pre-use Preparation

Inspect the watch glass for cracks, deformations, and smooth edges
Clean with ultrapure water or appropriate solvent to remove manufacturing residues
For trace analysis applications, soak in 10% nitric acid for 24 hours, rinse thoroughly with ultrapure water, and dry
Ensure the target vessel (beaker, dish, etc.) is clean and dry

II. Evaporation & Concentration

Transfer sample solution to the center of the watch glass — avoid overflow beyond edges
Place the watch glass in a water bath, oven, or on a hotplate — control temperature within 250℃
Partially cover the surface to control evaporation rate — adjust coverage as needed
After evaporation, carefully remove the watch glass using PTFE-coated tweezers or specialized tools

III. Covering & Dust Protection

Gently place the watch glass over the vessel opening — ensure complete coverage
PTFE is soft — no need to press down; a light placement is sufficient
For stability, place a lightweight object (e.g., stainless steel ring) on top if needed

IV. Cleaning & Maintenance

Routine Cleaning: Rinse promptly with ultrapure water after use — use lab detergent with a soft cloth or sponge
Stubborn Residues: Soak in dilute nitric acid — PTFE's non-stick surface makes cleaning easy
Sterilization: Autoclave (121℃, 15-20min) or dry heat sterilization
Important: Do not use hard brushes or abrasives — they may scratch the surface and affect non-stick performance
Storage: Store flat, avoid heavy objects that could cause deformation

V. Important Notes

PTFE is relatively soft — avoid dropping or impact with hard objects to prevent deformation or scratches
Do not use for high-temperature ashing (> 400℃)
Avoid contact with molten alkali metals (Na, K) and elemental fluorine
Verify oven or water bath temperature accuracy before use — calibrate regularly
Watch glass edges are thin — handle gently, avoid pinching edges firmly

💡 From a Seasoned Lab Technician: "Control evaporation rate — it's the key to consistent results" — PTFE conducts heat differently than glass. Temperature distribution needs to be more uniform. Place the watch glass on a pre-heated hotplate and ramp temperature slowly to avoid sample splashing or bumping from localized overheating.
To control evaporation rate, place a clean filter paper over the watch glass — this reduces dust contamination while regulating evaporation speed.
For crystallization, place the watch glass in a constant-temperature chamber with temperature stability within ±1℃ for more uniform crystal morphology.

Care & Notes

Show care & notes

⚠️ Safety & Compliance Checklist

Chemical Safety

Heating corrosive chemicals must be performed in a fume hood

Protective Equipment

Wear safety goggles, lab coat, and acid/alkali resistant gloves

Compliance

All operations should follow laboratory safety guidelines and relevant standards

Do not

Heating Safety: Use temperature-controlled equipment — avoid overheating

PTFE Watch Glass

Specifications

Product Description

I. Overview

II. Core Performance Parameters

III. Material & Workmanship

Applications

Solution Concentration

Crystallization

Dust Protection

Corrosive Sample Storage

Weighing Boat

Electron Microscopy Sample Prep

Selection Guide

I. By Application

II. By Vessel Compatibility

III. Material Selection

User Guide

I. Pre-use Preparation

II. Evaporation & Concentration

III. Covering & Dust Protection

IV. Cleaning & Maintenance

V. Important Notes

Care & Notes

Chemical Safety

Protective Equipment

Compliance

Need PTFE Watch Glasses?

PTFE Watch Glass

Specifications

Product Description

I. Overview

II. Core Performance Parameters

III. Material & Workmanship

Applications

Solution Concentration

Crystallization

Dust Protection

Corrosive Sample Storage

Weighing Boat

Electron Microscopy Sample Prep

Selection Guide

I. By Application

II. By Vessel Compatibility

III. Material Selection

User Guide

I. Pre-use Preparation

II. Evaporation & Concentration

III. Covering & Dust Protection

IV. Cleaning & Maintenance

V. Important Notes

Care & Notes

Chemical Safety

Protective Equipment

Compliance

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