Penetrant Testing
Reliable Penetrant Inspection for Non-Porous Metals. Get accurate, cost-effective surface flaw detection with fluorescent and visible dye penetrant testing, performed in our lab by certified professionals.
What Is Penetrant Testing?
Penetrant Testing (PT) is a non-destructive method used to detect surface-breaking defects in non-porous materials by applying a visible or fluorescent dye that reveals flaws through bleed-out.
Advantages of Penetrant Testing
- High Sensitivity to Surface Flaws: Reveals extremely fine cracks, pores, seams, and other surface-breaking defects invisible to the naked eye.
- Broad Material Compatibility: Works on ferrous and non-ferrous metals, ceramics, plastics, and other non-porous materials.
- Effective on Complex Geometries: Inspects contoured, threaded, or irregular surfaces without requiring disassembly or special fixtures.
- Flexible Method Selection: Offers both fluorescent (Type 1) and visible dye (Type 2) penetrants to suit various inspection environments.
- Batch-Friendly for High Volumes: Ideal for processing large quantities of small parts with consistent, repeatable results.
- Fast, Visual Results: Surface indications are clearly visible under white or UV light.
- Field-Deployable: Lightweight equipment and aerosol formats allow for convenient on-site inspections in remote or tight spaces.
- Cost-Efficient and Non-Destructive: A low-cost method that leaves the part unharmed and ready for continued use or further processing.
Limitations of Penetrant Testing
While penetrant testing is highly effective for detecting surface flaws, it does have a few limitations:
- Only detects surface-breaking defects
- Requires a non-porous, clean surface for accuracy
- Surface roughness and contamination can lead to false indications
- Test material must be thoroughly cleaned before and after inspection
- Multiple process steps must be controlled for consistent results
- Direct visual access to the surface is required
- Not suitable for high-temperature parts unless special procedures are used
- Chemical handling and waste disposal must follow proper safety protocols
Basic Principles of Penetrant Testing
Penetrant Testing (PT) involves applying a visible or fluorescent liquid penetrant to the clean surface of a non-porous part by spraying, dipping, or brushing. During the dwell time, the penetrant seeps into any surface-breaking flaws such as cracks or pores. After excess penetrant is removed, a developer is applied to draw out the trapped penetrant, forming visible indications of the defect.
Mitchell Laboratories performs both Type 1 (fluorescent) and Type 2 (visible dye) inspections.
Type 1 (Fluorescent): Uses a UV-reactive dye viewed under black light in a darkened booth for maximum sensitivity.
Type 2 (Visible Dye): Uses a bright red dye visible under white light, ideal for general-purpose inspections.
This method enhances visual detection by producing high-contrast, easily recognizable flaw indications—making even the smallest surface discontinuities clearly visible for accurate evaluation.
Common Applications
- Welds & Forgings
- Castings
- Fasteners & Pins
- Threaded Components
- Aerospace Hardware
- Round Bars & Shafts
- Surface Crack Detection
- Non-Porous Leak Detection
Quality Assurance & Compliance
- ISO 9001 & AS9100D Certified
Our procedures meet the latest ISO 9001 quality-management standards and AS9100D aerospace requirements. - ITAR Registered
Full compliance with International Traffic in Arms Regulations for defense and government work. - NADCAP Accreditation
Nadcap-approved processes at our Pico Rivera, Fontana, and South Gate facilities, ensuring industry-recognized special-process controls. - 100% Dimensional Traceability
Batch-lot tracking from raw material to final inspection report, with documented tolerances down to ±0.001″. - In-House Chemical & Metrology Labs
Real-time bath titration controls and precision measuring tools (CMM, optical comparator, micrometer) to verify every feature. - Qualified, Certified Personnel
Technicians trained per SNT-TC-1A and NAS 410 standards for penetrant testing, ensuring every inspection is performed by experts. - Continual Improvement Program
Regular internal audits and customer-driven process reviews to optimize quality and delivery.
Frequently Asked Questions
Type 1 uses fluorescent dye and requires UV light for inspection, offering superior flaw sensitivity. Type 2 uses red visible dye for inspection under white light—ideal for fieldwork or general surface inspection. Both are highly effective depending on the application.
PT is suitable for any non-porous metals such as aluminum, stainless steel, titanium, nickel alloys, and copper-based materials. It cannot be used on porous surfaces or rough castings.
Yes. Mitchell Laboratories has the capacity to inspect small to large parts, including those with complex geometries, blind holes, and machined profiles.
Lead times are quoted on a job-by-job basis. We do offer emergency and expedited turnaround options, and our team has decades of experience optimizing speed without compromising inspection quality.