Does a gasket really stop vapour at 90% RH?

Answer: It stops liquid water, not vapour. IP67 proves 1 m of immersion for 30 min; vapour still crosses EPDM at 0.1–0.3 g per day. The gasket handles splash; desiccant holds the long term.

Water on the inner wall after opening — is the case leaking?

Answer: Usually not. Air at 32 °C and 90% RH dew-points near 30 °C, so a 25 °C wall fogs within 30 s. Close the lid for 10 min: beads that clear were condensation, beads under one latch mean compression below 25%.

Can foam with mould spots stay in service?

Answer: No. Once spots show, hyphae reach 2–3 mm into the cell walls and wiping removes only the surface. Dry a 50×50×20 mm sample and retire the batch past 2% loss.

How often should desiccant be changed?

Answer: Every 6 months when sealing is good, sooner after five logged openings. Blue turning pink means internal RH passed 40%; without an indicator, retire a sachet at 20% weight gain.

Does an antifungal additive create compliance exposure?

Answer: It can, depending on chemistry. OBPA contains arsenic and is restricted in most EU consumer goods; IPBC is capped near 0.1%. Name the agent and dose in the file rather than writing treated.

How much gap does a stack need?

Answer: For Cases for SE Asia, 50 mm between cases, 50 mm off the wall, 100 mm off the roof. Under 30 mm the air speed falls below 0.1 m/s and local humidity runs 10–15 points high. ---

Cases for SE Asia: Humidity and Mould

Quick answer: Cases for SE Asia must hold a 28 °C, 85–90% RH internal climate with closed-cell foam, 20 g/m³ desiccant and drained grooves working together.

Internal climate on a coastal site
Condensation at the moment of opening
Foam water uptake and the mould threshold
Desiccant dose and replacement interval
Gasket grooves, drain holes and stacking
FAQ

1. Internal climate on a coastal site

Cases for SE Asia work in 28 °C and 85–90% RH most of the year. Closing a lid there seals wet air in: at 32 °C and 90% RH a cubic metre carries about 30 g of vapour, so a 60 L case brings 1.8 g with it.

The internal climate follows the shell. PP near 0.2 W/(m·K) with little thermal mass lets a 45 °C lid pull trapped air to 40 °C within 2 h, while a night drop to 24 °C leaves the interior lagging. A standing 4–6 °C gap condenses vapour and re-evaporates it.

Three sources feed that vapour, in unequal shares.

Source	Amount	Share	Fix
Air trapped at closing	1.8 g in 60 L	70%	Shorter lid time, desiccant
Foam and liner	3–5% by weight, open cell	20%	Closed-cell foam
Gasket groove	3–5 mL per metre	<10%	Drain holes, tilt

2. Condensation at the moment of opening

Condensation arrives in Cases for SE Asia within the first minute. Air at 32 °C and 90% RH has a dew point near 30 °C, so a 25 °C wall sits 5 °C past it and fogs at once; a 4 °C gap beads water within 30 s.

That film is not a leak. Close the lid for 10 min and reopen: beads that clear were condensation, while beads that stay under one latch mean compression below 25–30%.

Cases for SE Asia are handled three ways. Open in an air-conditioned room or shade, where 24 °C and 55% RH keeps the gap under 2 °C. Hold each opening below 30 s and below two per hour. Add an indicator sachet to flag uptake before the foam shows it.

Cases for SE Asia standing open in shallow water, orange shell beaded with droplets, black foam cavities and four latches

3. Foam water uptake and the mould threshold

Foam is the biggest reservoir inside. EVA is closed cell at under 1% uptake in 24 h; EPE and PU are open cell at 3–5%, holding 3–5 times more in the same air. Uptake predicts mould better than density does.

For Cases for SE Asia the threshold is 75% RH held for 48 h: past that most spores germinate, and a week brings visible spots. A 40 ft box runs 80–90% for 14 days at sea, squarely inside that window.

Antimicrobial and antifungal are separate jobs. Silver zirconium phosphate at 0.3–0.8% targets bacteria, not mould. OBPA contains arsenic and is restricted in most EU consumer goods; IPBC is commonly capped near 0.1%.

Uptake can be checked in house: dry a 50×50×20 mm sample at 105 °C for 2 h and treat any loss above 2% as wet.

Foam	Cells	24 h uptake	Mould risk
EVA	Closed	<1%	Low
EPE	Open	3–5%	Medium
PU	Open	3–5%	High

4. Desiccant dose and replacement interval

Cases for SE Asia start at 20 g/m³ and then add margin. A 60 L case is 0.06 m³, so the base dose is 1.2 g; two 5 g sachets go in, covering four or five openings across 6 months. A gasket that stops sealing doubles the figure.

Set the interval at 6 months, not the sachet shelf life. Silica gel saturates in 2–3 weeks in open 90% RH air and lasts half a year inside an IP67 shell. Log any opening past 10 min and replace early after five.

Placement decides efficiency: hang the sachet in the lid where convection carries vapour to it, never under the load. Split across four corners and uptake runs about 40% faster.

Volume	20 g/m³ base	Fitted	Interval
60 L	1.2 g	5 g × 2	6 months
120 L	2.4 g	10 g × 2	4 months

5. Gasket grooves, drain holes and stacking

The gasket groove in Cases for SE Asia is where water collects. EPDM seals on a continuous line only at 25–30% compression, and the groove holds 3–5 mL per metre; laid flat, it leaks inward daily.

Drain holes and angle solve it. Drill Ø3 mm at the lowest point every 200 mm, deburr the edge, and ship at a 2° tilt. Never drill under a latch, where compression peaks.

In the box, leave air gaps: 50 mm between cases, 50 mm off the wall, 100 mm off the roof, with 0.5 m/s of movement. A tight stack runs 10–15 points wetter on the blind face.

A 30 min logger beats judgement for Cases for SE Asia: a curve past 85% within 48 h of loading says the wet air went in at closing, and that batch should be opened within 7 days.

Cases for SE Asia in white and blue, lid open to show grey foam, a white gasket seam and blue corner bumpers

Conclusion

Moisture control for Cases for SE Asia is a chain, not a sachet: less wet air at closing, closed-cell foam under 1% uptake, a drained groove, 50 mm of air gap, and 20 g/m³ of desiccant covering 6 months of permeation. Break one link and the rest cannot compensate. A 30 min logger curve held under 60% is the verdict.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.