Shipping rust-prevention methods compared
VCI Paper vs Silica Gel vs Rust Inhibitor
Choose the rust-prevention method for storage/shipping
3 mechanisms — VCI vapour (MIL-PRF-3420), silica gel desiccant (Mil-D-3464), liquid film (Tectyl/Cosmoline/ORAFON). Rust protection from 6 months to 10 years + COA for military / SRT / export
In short — which one?
Decide on 3 factors — storage life, packaging format, removal before use. VCI = 30-60 day export, silica = cabinets / small boxes, rust inhibitor = long life 5-10 years
EXPORT SHIPPING
VCI Paper / Film
- MIL-PRF-3420 multi-metal cert
- 2-5 years in a sealed bag
- Unwrap and use immediately — no washing
- Price ฿140-240/m² (80 gsm paper)
Best for
Sea-freight export 30-60 days, military spares (MIL-PRF-3420), automotive aftermarket
CABINET / ELECTRONICS
Silica Gel
- Mil-D-3464E Type I/II passes TORs
- Cuts RH < 50% in a sealed system
- Indicator card shows when saturated
- Price ฿4-15/sachet — the cheapest
Best for
Tool cabinets, electronics packaging, optical lenses, small spare parts, kits of parts
LONG-TERM (5-10 years)
Liquid Rust Inhibitor
- Thick film 30-500 µm
- Works outside a sealed system
- Tectyl 506 ASTM B117 1,000 hr
- Cosmoline 10+ years (mothballing)
Best for
Locomotive / wagon spares, military preservation, long-stored machine parts, outdoor storage
Full spec comparison table
| Item | VCI Paper / Film | Silica Gel | Liquid Rust Inhibitor |
|---|---|---|---|
| Protection mechanism | Volatile amine vapour deposits a molecular film on the steel surface | Physical adsorbent pulls moisture from the air → RH < 50% | Wax/oil film applied directly, 30-500 µm |
| Service life (sealed) | 2 – 5 years (sealed bag/container) | 6 – 18 months (depends on size + volume) | ORAFON 2-5 years · Tectyl 5-10 years · Cosmoline 10+ years |
| Needs a sealed system? | ✓ Must be sealed tight — stretch film + heat-seal | ✓ Must be 100% sealed (otherwise hydrates within days) | Not required — the film sits directly on the surface |
| Compatible metals | Multi-metal (steel/copper/brass/aluminum) MIL-PRF-3420 | All metals (neutral desiccant) | Steel + cast iron + bronze (check the data sheet) |
| Key standards | MIL-PRF-3420G + ASTM A924 + ISO 21006 | Mil-D-3464E Type I/II + ASTM E96 | ASTM D1748 (humidity) + ASTM B117 (salt spray) |
| Application | Wrap / place in a bag — works immediately (no surface contact needed) | Place sachets in the box — indicator turns from blue/orange to pink/green when saturated | Spray / brush / dip — film dries in 30 min to 2 h |
| Removal before use | Tear open — steel ready to use immediately (film dissipates in air) | Discard the sachet | **Must be washed off** with IPA / solvent before use on some parts |
| Indicator card / sensor | None (works via vapour) | Humidity indicator card 10/20/30% RH inside the box | None (visual check — dry / flaking) |
| Average cost per piece (5-10 kg part) | ฿80 – 180 (80 gsm paper + bag) | ฿20 – 60 (4 × 30 g sachets) | ฿120 – 350 (one spray coat + dry) |
| Material price (Bangkok 2026) | VCI paper 80 gsm ฿140-240/m² · VCI bag ฿8-45/bag | Silica gel ฿4-15/sachet 8-32 g (MOQ 1,000) | ORAFON ฿180-320/L · Tectyl ฿580-980/L · Cosmoline ฿1,200-2,500/L |
| Accepted in government TORs | ✓ Military (Ordnance / Royal Thai Navy) + SRT + export | ✓ Every TOR packing steel / electronics | ✓ SRT (locomotive / wagon spares) + agro-industry |
| Saha brand + lead time | KraftPro 80/100/125 gsm — Bangkok 3-5 days | Mil-D-3464E orange indicator — Bangkok 2-3 days | ORAFON Rust Stop Bangkok 1-2 days · Tectyl/Cosmoline 4-6 weeks |
References: MIL-PRF-3420G (VCI paper, 2019), ASTM A924 (VCI test method), Mil-D-3464E (silica gel, 1987), ASTM D1748 (humidity cabinet test), ASTM B117 (salt spray), ASTM D3951 (Commercial Packaging — export). Average Thai market prices, May 2026 — at government minimum MOQ, prices are 10-25% better
How many months will the steel parts be stored, and how far are they shipped?
Tell us the part (weight + size) + storage period (months/years) + shipping mode (domestic / sea / air) → we promptly send VCI/silica/Tectyl specs from 2-3 brands + mil-spec COA + budget + lead time
Related comparisons
Decide with confidence — compare from several angles
Read the related comparison tables — full specs, real prices, and a recommendation for each use.
FAQ
Common Questions
Q1.VCI vs Silica Gel vs Rust Inhibitor — how do they work differently?+
**Three different mechanisms** — choose by storage duration + packaging type:
• **VCI Paper / Film (Volatile Corrosion Inhibitor)** — paper/film coated with amine-based inhibitor (ammonium benzoate / sodium nitrite) that slowly evaporates and adsorbs onto steel surfaces as a molecular film. **Works in closed or semi-closed systems** (boxes/bags/containers). Service life 2-5 years sealed
• **Silica Gel (Desiccant)** — physically adsorbs moisture from air (no chemical reaction). Reduces RH < 50% → corrosion stops. **Requires fully sealed enclosure**. Dosage scales by air volume (1 packet 30 g per 5 L air). Service life 6-18 months
• **Rust Inhibitor (Liquid film)** — coats steel directly with oil/wax film — Tectyl / Cosmoline / ORAFON Rust Stop. **Thickest film** — protects even outside enclosure. Service life 5-10 yrs indoor, 1-3 yrs outdoor
**Rule:** High-value + long storage + returnable spares → **Rust Inhibitor**. Ocean freight + quick unwrap → **VCI Paper**. Cabinet/room humidity control → **Silica Gel**
Q2.MIL-PRF-3420 vs ASTM A924 vs Mil-D-3464 — what's the difference?+
Three main standards cited in Thai government TORs (Defense Procurement, Royal Thai Navy, SRT spare parts warehouse):
• **MIL-PRF-3420G** (US Military, 2019 ed.) — VCI paper for military spares. Requires VCI loading ≥ 13.5 g/m² + ≥ 2-year protection sealed + non-carcinogenic amine (replacing old sodium nitrite). Multi-metal grade for steel, copper, brass, aluminum
• **ASTM A924** (American Society for Testing) — VCI testing methodology used to verify performance across brands. Test methods: bell jar 60 days + hot-cold cycle
• **Mil-D-3464E** (US Mil, updated 1987) — silica gel mil-spec. Defines cobalt-free indicator dye (new — old used cobalt chloride blue→pink), **Type I** (8 g packet) for small boxes, **Type II** (16/32 g packet) for large boxes/containers
• **ISO 21006** (International) — VCI multi-metal performance, rarely cited in Thai TORs
**Most Thai government TORs** cite MIL-PRF-3420 (VCI) + Mil-D-3464 (silica) together. **Never use non-mil-spec VCI/silica** for military/aerospace work
Q3.Shipping steel spare parts Thailand → Europe — what to use?+
**Standard export procedure for 30-60 day transit + 70-95% RH + salt air:**
1. **Clean** — light sand + wipe clean, remove finger oil with IPA
2. **Apply VCI Oil / Rust Inhibitor** — thin coat on surface (small parts) or spray Tectyl 506 (large parts / automotive)
3. **Wrap with VCI Paper** or place in VCI Bag (must be multi-metal MIL-PRF-3420)
4. **Add Silica Gel** 30-60 g per 1 m³ air volume (reduce initial humidity)
5. **Insert humidity indicator card** (10% / 20% / 30% RH) on box — destination check
6. **Seal with stretch film + vacuum seal** (if possible) or heat-seal the bag opening
7. **Export labeling** — ASTM D3951 (Commercial Packaging) for EU/USA, GB/T 13384 (China)
**What we carry:** VCI film · VCI bags · desiccant — no VCI paper and no liquid rust inhibitors (/en/rust)
Q4.Does Sahawatthanakit sell liquid rust inhibitors (e.g. Tectyl / Cosmoline)?+
No — we do not sell liquid rust inhibitors. For storage and shipping protection we carry VCI Anti-Corrosion Film · VCI Anti-Corrosion Bag · Desiccant Moisture Absorber (/en/rust)
Q5.Which storage and shipping rust-protection products does Sahawatthanakit carry?+
We carry VCI Anti-Corrosion Film · VCI Anti-Corrosion Bag · Desiccant Moisture Absorber — no VCI paper and no liquid rust inhibitors. Send the part size, quantity and storage time on LINE OA @sahawatt1988 for a price.
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