IP67 vs IP68 Magnets: What the Rating Actually Means for Sourcing

IP ratings were not designed for magnets

IP (Ingress Protection) ratings — defined by IEC 60529 — were designed for electronic enclosures: switchgear panels, junction boxes, instrument housings. The test protocol places a complete enclosure in a water tank or under a spray nozzle and checks whether water reaches the internal electronics.

A standalone magnet is not an enclosure. When a supplier stamps "IP67" or "IP68" on a magnet listing, one of three things is true:

They tested the housing/assembly the magnet sits inside — not the magnet itself
They are describing the encapsulation's theoretical capability — without third-party test data
They are copying marketing language from competitors — with no test basis at all

Understanding this distinction prevents specification errors that lead to field failures.

IP ratings describe test conditions, not material durability. For magnets, waterproofing = encapsulation method, not a simple IP number.

What IP67 and IP68 actually test

Rating	Dust test	Water test	Duration
IP6X	8 hours in talcum powder chamber, under 2 mg ingress	—	8 h
IPX7	—	Full immersion at 1 m depth	30 min
IPX8	—	Continuous immersion at specified depth	Manufacturer-stated
IP67	Dust-tight + 1 m immersion	Combined	8 h dust + 30 min water
IP68	Dust-tight + deep immersion	Combined	8 h dust + continuous water

What these tests do NOT cover

Real-world condition	IP test coverage	Actual test needed
Salt spray corrosion	❌ Not tested	ASTM B117 (salt fog)
High-pressure wash-down	❌ Not tested	IPX9K (80 °C, 80–100 bar)
Thermal cycling	❌ Not tested	Custom cycle (e.g., −40 to +85 °C, 500 cycles)
UV degradation	❌ Not tested	ASTM G154 (UV-A or UV-B accelerated aging)
Chemical immersion	❌ Not tested	Material compatibility per ASTM D471
Long-term outdoor exposure	❌ Not tested (30 min only)	Real-time or accelerated weathering
Mechanical vibration impact on seals	❌ Not tested	Custom vibration profile

Key insight: a magnet that passes IP67 immersion for 30 minutes may develop corrosion within 3 months in a Gulf Coast outdoor installation due to salt air — because salt spray resistance is a completely separate property from water immersion resistance.

How encapsulated magnets actually achieve waterproofing

Method 1: Rubber overmold (most common for pot magnets)

The magnet core is placed in a compression or injection mold, and rubber (usually NBR, EPDM, or silicone) is vulcanized around it.

Seal integrity depends on:

Bonding agent (primer) between rubber and magnet surface — critical step
Flash-line control at the mold parting line (common weak point)
Post-mold inspection (visual + pull test)

Rubber compound	Water-tightness	Salt spray (ASTM B117)	Temperature range
NBR	IP67 equivalent	500–1000 h	−30 to +100 °C
EPDM	IP67 equivalent	500–1000 h	−40 to +130 °C
Silicone (VMQ)	IP67–IP68	1000+ h	−60 to +200 °C

Typical failure mode: delamination at the rubber–magnet interface due to poor primer application. If you can peel the rubber off the magnet with pliers, the mold process is inadequate.

Method 2: Stainless steel cup + epoxy/sealant

A machined or deep-drawn stainless cup houses the magnet. The open face is sealed with epoxy, rubber gasket, or threaded cap.

Seal integrity depends on:

Cup material grade (304 vs 316L — 316L for marine/salt environments)
Seal method: epoxy potting, O-ring groove, or interference fit
Gap dimension: epoxy seal thickness should be ≥0.5 mm to prevent cracking

Cup material	Typical IP	Salt spray	Cost (Ø20mm pot)
304 SS + epoxy seal	IP67	200–500 h	$1.50–3.00
316L SS + rubber gasket	IP68	1000–2000 h	$3.00–6.00
316L SS + O-ring + threaded cap	IP68 (deep water)	2000+ h	$5.00–10.00

Method 3: Full plastic encapsulation

The magnet is insert-molded or potted inside a plastic housing (typically Nylon PA6/PA66, POM, or ABS).

Seal integrity depends on:

Plastic shrinkage after cooling (can create micro-gaps around the magnet)
Moisture absorption of the plastic (PA6 absorbs 2–3% water — POM absorbs under 0.5%)
Wall thickness over the magnet face (affects both seal and pull force)

Pull force loss from encapsulation

Every encapsulation method puts non-magnetic material between the magnet and the contact surface:

Encapsulation	Non-magnetic gap	Pull force loss (approx.)
Epoxy clear-coat (20 µm)	0.02 mm	~1%
Thin rubber pad (0.5 mm)	0.5 mm	~15%
Standard rubber overmold (1.5 mm)	1.5 mm	~35%
Thick rubber overmold (3 mm)	3.0 mm	~60%
Stainless cup (0.8 mm wall)	0.8 mm	~20%
Plastic encapsulation (1.0 mm)	1.0 mm	~25%

Critical RFQ point: always specify pull force at the encapsulated surface, not the bare magnet spec. A "20 kg" magnet with 2 mm rubber typically delivers only ~10 kg at the contact face.

Every mm of non-magnetic coating between magnet and contact surface reduces pull force. At 2mm rubber thickness, expect ~50% of bare magnet rating. Always specify pull force at the coated surface.

How to specify waterproof magnets correctly

Don't write this:

"Need IP67 waterproof magnets, 20mm diameter, rubber coated"

This tells the supplier nothing about the actual environment and invites the cheapest interpretation.

Write this instead:

Application: outdoor LED sign mounting bracket on aluminum frame

Magnet type: pot magnet, Ø20 × 6mm, rubber overmold (EPDM preferred for UV stability)

Pull force: ≥8 kg at the rubber contact surface

Environment: permanent outdoor installation, coastal Australia (salt air), −5 to +55 °C, direct UV exposure

Required testing: salt spray ≥500 h (ASTM B117), no visible corrosion on magnet under rubber

Volume: 2,000 pcs initial order, 8,000 pcs/year

Packaging: individual poly bags in moisture barrier master carton

Supplier qualification: what to ask for

When evaluating a waterproof magnet supplier, request:

Cross-section photos of the encapsulated magnet — shows rubber thickness consistency and bond quality
Salt spray test report — should reference ASTM B117 with specific hours and pass/fail criteria
Peel adhesion test result — rubber-to-magnet bond ≥2 N/mm (ISO 813)
Compound datasheet — confirms specific rubber grade, not just "rubber"
Dimensional inspection report — coated OD tolerance, typically ±0.2mm for rubber overmold
First-article inspection (FAI) — pull force measurement at coated surface vs specification

If a supplier cannot provide cross-section photos and a salt spray report, their waterproofing claim is unverified.

IP ratings were not designed for magnets

A standalone magnet is not an enclosure. When a supplier stamps "IP67" or "IP68" on a magnet listing, one of three things is true:

They tested the housing/assembly the magnet sits inside — not the magnet itself
They are describing the encapsulation's theoretical capability — without third-party test data
They are copying marketing language from competitors — with no test basis at all

Understanding this distinction prevents specification errors that lead to field failures.

IP ratings describe test conditions, not material durability. For magnets, waterproofing = encapsulation method, not a simple IP number.

What IP67 and IP68 actually test

Rating	Dust test	Water test	Duration
IP6X	8 hours in talcum powder chamber, under 2 mg ingress	—	8 h
IPX7	—	Full immersion at 1 m depth	30 min
IPX8	—	Continuous immersion at specified depth	Manufacturer-stated
IP67	Dust-tight + 1 m immersion	Combined	8 h dust + 30 min water
IP68	Dust-tight + deep immersion	Combined	8 h dust + continuous water

What these tests do NOT cover

Real-world condition	IP test coverage	Actual test needed
Salt spray corrosion	❌ Not tested	ASTM B117 (salt fog)
High-pressure wash-down	❌ Not tested	IPX9K (80 °C, 80–100 bar)
Thermal cycling	❌ Not tested	Custom cycle (e.g., −40 to +85 °C, 500 cycles)
UV degradation	❌ Not tested	ASTM G154 (UV-A or UV-B accelerated aging)
Chemical immersion	❌ Not tested	Material compatibility per ASTM D471
Long-term outdoor exposure	❌ Not tested (30 min only)	Real-time or accelerated weathering
Mechanical vibration impact on seals	❌ Not tested	Custom vibration profile

How encapsulated magnets actually achieve waterproofing

Method 1: Rubber overmold (most common for pot magnets)

The magnet core is placed in a compression or injection mold, and rubber (usually NBR, EPDM, or silicone) is vulcanized around it.

Seal integrity depends on:

Bonding agent (primer) between rubber and magnet surface — critical step
Flash-line control at the mold parting line (common weak point)
Post-mold inspection (visual + pull test)

Rubber compound	Water-tightness	Salt spray (ASTM B117)	Temperature range
NBR	IP67 equivalent	500–1000 h	−30 to +100 °C
EPDM	IP67 equivalent	500–1000 h	−40 to +130 °C
Silicone (VMQ)	IP67–IP68	1000+ h	−60 to +200 °C

Typical failure mode: delamination at the rubber–magnet interface due to poor primer application. If you can peel the rubber off the magnet with pliers, the mold process is inadequate.

Method 2: Stainless steel cup + epoxy/sealant

A machined or deep-drawn stainless cup houses the magnet. The open face is sealed with epoxy, rubber gasket, or threaded cap.

Seal integrity depends on:

Cup material grade (304 vs 316L — 316L for marine/salt environments)
Seal method: epoxy potting, O-ring groove, or interference fit
Gap dimension: epoxy seal thickness should be ≥0.5 mm to prevent cracking

Cup material	Typical IP	Salt spray	Cost (Ø20mm pot)
304 SS + epoxy seal	IP67	200–500 h	$1.50–3.00
316L SS + rubber gasket	IP68	1000–2000 h	$3.00–6.00
316L SS + O-ring + threaded cap	IP68 (deep water)	2000+ h	$5.00–10.00

Method 3: Full plastic encapsulation

The magnet is insert-molded or potted inside a plastic housing (typically Nylon PA6/PA66, POM, or ABS).

Seal integrity depends on:

Plastic shrinkage after cooling (can create micro-gaps around the magnet)
Moisture absorption of the plastic (PA6 absorbs 2–3% water — POM absorbs under 0.5%)
Wall thickness over the magnet face (affects both seal and pull force)

Pull force loss from encapsulation

Every encapsulation method puts non-magnetic material between the magnet and the contact surface:

Encapsulation	Non-magnetic gap	Pull force loss (approx.)
Epoxy clear-coat (20 µm)	0.02 mm	~1%
Thin rubber pad (0.5 mm)	0.5 mm	~15%
Standard rubber overmold (1.5 mm)	1.5 mm	~35%
Thick rubber overmold (3 mm)	3.0 mm	~60%
Stainless cup (0.8 mm wall)	0.8 mm	~20%
Plastic encapsulation (1.0 mm)	1.0 mm	~25%

Critical RFQ point: always specify pull force at the encapsulated surface, not the bare magnet spec. A "20 kg" magnet with 2 mm rubber typically delivers only ~10 kg at the contact face.

Every mm of non-magnetic coating between magnet and contact surface reduces pull force. At 2mm rubber thickness, expect ~50% of bare magnet rating. Always specify pull force at the coated surface.

How to specify waterproof magnets correctly

Don't write this:

"Need IP67 waterproof magnets, 20mm diameter, rubber coated"

This tells the supplier nothing about the actual environment and invites the cheapest interpretation.

Write this instead:

Application: outdoor LED sign mounting bracket on aluminum frame

Magnet type: pot magnet, Ø20 × 6mm, rubber overmold (EPDM preferred for UV stability)

Pull force: ≥8 kg at the rubber contact surface

Environment: permanent outdoor installation, coastal Australia (salt air), −5 to +55 °C, direct UV exposure

Required testing: salt spray ≥500 h (ASTM B117), no visible corrosion on magnet under rubber

Volume: 2,000 pcs initial order, 8,000 pcs/year

Packaging: individual poly bags in moisture barrier master carton

Supplier qualification: what to ask for

When evaluating a waterproof magnet supplier, request:

Cross-section photos of the encapsulated magnet — shows rubber thickness consistency and bond quality
Salt spray test report — should reference ASTM B117 with specific hours and pass/fail criteria
Peel adhesion test result — rubber-to-magnet bond ≥2 N/mm (ISO 813)
Compound datasheet — confirms specific rubber grade, not just "rubber"
Dimensional inspection report — coated OD tolerance, typically ±0.2mm for rubber overmold
First-article inspection (FAI) — pull force measurement at coated surface vs specification

If a supplier cannot provide cross-section photos and a salt spray report, their waterproofing claim is unverified.