Common Questions

Frequently Asked Questions

Answers to common questions about hard anodising, materials, specifications, and turnaround times. Based in Henderson, Auckland.

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Technical QuestionsMaterials & SpecificationsCommercial & PracticalIndustries & Applications

Technical Questions

Hard anodising gives you increased corrosion resistance, wear resistance, electrical insulation, and high temperature resistance. The coating won't degrade under UV light like paint or powder coat. You can dye it black if needed.
No. When we say 60µm thickness, that's 50% penetration into the base metal and 50% buildup on the surface. It's not like plating or paint which sits entirely on top. The exact ratio varies slightly depending on your alloy, but it's roughly half and half.
Yes. We need firm electrical contact during the process, so each rack point leaves a small uncoated spot. Tell us where the non-critical areas are when you drop off your parts. We'll rack accordingly.
Type III Class 1 (undyed) comes out a green-brownish colour with a matte to semi-matte finish. Type III Class 2 is dyed black. The coating follows the existing surface finish — if you machine it to 1.6Ra, you'll get a smooth anodised finish. Rougher machining gives a rougher result.
Yes, but it's not simple. You need caustic chemicals and it removes material from the base aluminium. If you're thinking of stripping and re-anodising, talk to us first because you might lose dimensional tolerance.

Anodising converts the aluminium surface into aluminium oxide. It's part of the metal, not a layer on top.

Powder coat is a plastic film that sits on the surface. Anodising won't chip or peel, handles higher temperatures (up to 200°C continuously), and doesn't degrade in UV. Powder coat gives you more colour options and can hide surface imperfections better.

Sulphuric acid anodising (Type II) runs at room temperature and gives you a 12-25µm coating.

Hard anodising (Type III) runs cold (around 0-5°C) with higher voltage, producing a 60µm coating that's significantly harder and more wear-resistant. Type II works fine for architectural and decorative applications. Type III is for parts that take a beating.

Materials & Specifications

No. We can anodise aluminium and magnesium alloys. Steel, stainless, brass, and copper need different processes. If you're not sure what you have, bring a sample and we'll check it.
5000, 6000, and 7000 series work well. So do 355, 356 cast alloys and 319 die-cast. Keep copper content under 3.5% and silicon under 5% if you want good results. 6061 and 6082 are common in NZ fabrication and both anodise well.
Yes. Magnesium has a good strength-to-weight ratio but corrodes easily. Anodising it significantly improves corrosion resistance. Common for aerospace and racing components where weight matters.
Type II (standard anodising) gives you 12µm coating thickness. Type III (hard anodising) gives you 60µm. Type III is harder, more wear-resistant, and better for parts under load or in harsh conditions. Type II costs less and works fine for architectural extrusions, handrails, and decorative applications.
Yes, if they're 355, 356, or 319 alloys. Cast parts often have porosity which can show up after anodising as dark spots. Die-cast parts with high silicon content (above 8-10%) don't anodise well and come out grey or streaky. Send us a sample piece if you're unsure.
2000 series (high copper content) has good mechanical properties but it's difficult to hard anodise. You'll get a darker, less uniform finish. If you need hard anodising for strength reasons and you're speccing the material yourself, choose 7075 instead of 2024.
It helps. If you know the alloy, tell us. If you don't, bring a sample and we'll advise whether it'll anodise well. Some alloys look identical but anodise completely differently.

Commercial & Practical

Depends on part size, quantity, and coating spec. Type III costs more than Type II because of longer processing time and the thicker coating. Small batch jobs cost more per piece than production runs. Phone us on 09 836 8889 or email dimensions and quantities for a quote.

Type II is usually 5-7 working days. Type III takes 7-10 working days. Rush jobs might be possible depending on what's in the tanks. Call us if you're up against a deadline.

Yes. Our tanks in Henderson handle substantial parts for marine, aerospace, and industrial jobs. Email us your dimensions and we'll confirm whether it fits.

Sometimes. It depends on current workload and tank schedule. We'll try to accommodate genuine emergencies but can't always guarantee it. Call us early and we'll see what we can do.
No hard minimum, but small one-off jobs cost more per piece because of setup time. If you've got a single prototype part, we can do it. If you're running production, we'll give you better pricing on batch quantities.
For large orders or regular customers, yes. For small jobs, dropping off at Henderson is usually easier. Talk to us about logistics when you book the job.

Industries & Applications

Marine fittings and hardware, defence and military equipment, aerospace components, medical instruments, automotive performance parts, and precision tooling. Any application where you need extreme wear resistance and corrosion protection in harsh conditions.
Yes. We do a lot of marine work around Auckland. Type III hard anodising handles saltwater exposure well. Boat fittings, cleats, winches, and deck hardware all benefit from the corrosion resistance. We run Type II Marine Class (25µm) for semi-hard applications if you don't need full Type III.
We can meet many aerospace specifications. If you have a specific mil-spec or AS/NZS standard to meet, send us the documentation and we'll confirm whether we can certify to it.
Yes. Hard anodising is commonly used on medical instruments because it's corrosion-resistant, biocompatible, and handles repeated sterilisation cycles. The hard surface resists wear from surgical use.
Type III hard anodising passes 1000+ hours in neutral salt spray (ASTM B117) when properly sealed. Type II typically passes 500-1000 hours depending on coating thickness. If you need specific salt spray performance, tell us the required hours and we'll spec the process accordingly.

Still have questions?

Phone us on 09 836 8889 or send us an email with your component details.

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