Aluminium Coatings

Aluminium coatings are generally used due to their very high reflectivity, and their heat dissipation - however they have a few disadvantages that need to be considered.

• Very high reflectivity
• Used for laser ablation
• Not commonly held in stock
• Surface very delicate and can damage easily

We don’t hold a very large stock of Aluminium coated products, in fact only a handful of product types are available, so it is always advisable to speak to one of our technical sales team to discuss the availability in more detail before deciding on this option.

Aluminium – when coated at the same thickness as chrome – is very highly reflective. At a normal thickness of 1000@ angstroms, we can state the reflectivity at 78% - 85%. However, the visual appearance of the reflectivity of the aluminium is directly affected by the thickness of the film itself - so , as the thickness goes up the film takes on a “dull foggy” appearance. The reason is, the aluminium crystal formation reflects back directionally like a cone rather than straight back like a mirror. When measuring the beam that is reflected, only a small part of the beam is captured so most measuring equipment thinks that reflectivity is in the 25% range – but in fact, the actual reflectivity of “foggy “ aluminium is the same as “shiny” aluminium.

So, the first main usage of Aluminium is higher reflectivity – at an average of 80% in the visible spectrum, that is 20% higher than bare chrome which is a significant amount.

The 2nd main use is for laser ablation. Due to the reflectivity, some customers successfully use the aluminium coatings as a mask during laser ablation. The laser reflects back from the surface more than chrome, so there is less heat build up and less chance for breakages. When using the plates for this application, we generally recommend a much thicker coating of Aluminium to reduce the damage to the surface. This is where the “foggy aluminium” is used.

The biggest disadvantage to Aluminium is that it can be damaged very easily. The metal coating is much less durable than chrome and can cause problems when cleaning. In fact, it can be removed from the surface by a simple hard rub with a cloth.