Manufacturer · Fashion & Home Accessories
The same finish on brass and on zinc alloy often looks different: on brass the tone is usually warmer and deeper, while on zinc alloy it is lighter, greyer or more mirror-like. The difference comes from the base metal, from the surface of the part and from the way it is made. That is why in the Polkom colour chart every code in the G and M series is shown in two versions – B (brass) and A (zinc alloy).
Below you will see real samples from the chart where the difference is clearest, and the practical conclusions for collections in which buttons, snap buttons, eyelets and buckles must look the same.
Why brass and zinc alloy give a different colour with the same finish
The finish on metal accessories is a thin layer: electroplating, toning or lacquer, often with additional ageing (antique). The thinner and more transparent the layer, the more the metal underneath shows through. Three factors determine the final tone:
- Colour of the base metal. Brass is an alloy of copper and zinc with its own warm, yellowish colour. Zinc alloy is light grey with a cool cast. With satin, antique and semi-transparent finishes this undertone shows and shifts the final colour.
- Surface of the part. Brass parts are most often stamped and pressed from sheet, while zinc alloy parts are die-cast. A casting has a different microstructure and after polishing reflects light differently, often more like a mirror.
- Shape and relief. Cast styles allow deeper relief. With antique finishes the dark tone stays in the recesses, while the raised areas are wiped lighter. So a button with more relief looks more contrasting, even though the code is the same.
Samples from the colour chart: B and A pairs
Here are four codes where the two metals differ most visibly. On the left is the brass version, on the right the zinc alloy version.
The table summarises the comparison of the samples in our chart. It shows the direction of the difference, not an exact value. Final approval is always made on a physical sample.
| Code and tone | Brass (B) | Zinc alloy (A) | What to bear in mind |
|---|---|---|---|
| PK-M03 Light satin bronze | lighter, pinkish champagne | darker bronze | the biggest difference in the chart – do not mix the two metals in one style |
| PK-M12 Satin rose gold | rich rose gold | much lighter, pale pink | choose the version depending on how “pink” the accent should be |
| PK-M09 Satin gunmetal | visibly lighter | darker | here brass is the light version – the direction is not always the same |
| PK-M47 Black gunmetal gloss | darker | visibly lighter | approve the two items side by side |
| PK-M07 Yellow brass gloss | rich yellow | paler and more mirror-like | for a classic “gold” look brass is more suitable |
| PK-G03 Light mirror silver | warm, light silver | greyer | the difference shows on light fabrics |
| PK-G16 Mirror rose silver | rose silver | visibly lighter, with a pink cast | for womenswear collections compare in daylight |
| PK-M75 Antique pewter grey | cool pewter grey | warmer, closer to brass | a good example that zinc alloy is not always cooler |
| PK-M83 Antique silver with patina | even patina | darker, brownish centre | the relief of the style intensifies the effect |
When the difference is large and when it is barely visible
The difference is strongest with:
- satin and semi-transparent tones – bronze, rose gold, champagne;
- antique finishes, where part of the dark layer is wiped off and the metal beneath shows;
- light tones, where every undertone shows immediately.
The difference is small with solid dark finishes such as deep black and dark graphite. The lacquer and effect finishes of the P series cover the metal with a solid layer and are shown in the chart in one version, without a B and A split.
One style – one metal
The most common mistake looks like this: a coat has cast relief buttons in zinc alloy and brass snap buttons on the pockets, ordered in the same code. Separately both look good, but side by side the difference is visible. Here is how to avoid it:
- Decide on the material together with the colour. In the tech pack, write the full code with the letter, for example PK-M76-B.
- If two positions on one garment are in different metals, ask for samples of both and approve them side by side, on the fabric.
- Do not change the material on a repeat order without approving a new sample.
- Compare in daylight and under the lighting in which the garment will be sold.
Which accessories are most often made of which metal
Snap buttons, eyelets and rivets are most often stamped from brass. Shaped buttons with deep relief, metal logo plates and many metal buckles are cast from zinc alloy. So in one collection the two metals almost always appear together, and matching the colour between them is a separate task.
Brass or zinc alloy – how to decide by colour
- Brass (B), if you want a warm, rich tone and a classic antique look, especially with yellow gold, brass and copper.
- Zinc alloy (A), if you are looking for a lighter or more mirror-like effect, or a style with a complex shape and deep relief, where the contrast of the antique finish will show well.
- The same version as the approved one, if the collection already has an established code. Match new items to it, not just to the number in the chart.
The choice of metal also depends on strength, weight and shape, not only on colour. Here we look only at colour: how much the same tone changes and how to control it. Browse all metal buttons to see which styles are cast and which are stamped.
Nickel free on both metals
All Polkom metal finishes, on brass and on zinc alloy, are nickel free. Names such as “nickel”, “black nickel” or “silver” describe only the colour of the finish, not its composition. This applies to all codes in the colour chart.
Samples and orders from the manufacturer
Polkom is a manufacturer of metal accessories for fashion, furniture, footwear and bags with over 30 years of experience. Choose codes from the finish colour chart, state the metal (B or A) and the items and send us an inquiry. We will prepare samples so that you can approve the colour of all metal parts side by side before production.
