Cost to provide choice of colours

[Jethro_uk]

We've finally managed to save enough for a new wheelchair for SWMBO. Going for an Invacare "Active" model, we'd scoped out before Xmas.

Just had a call from the shop saying that the colour we originally chose has been discontinued, and they emailed the new chart.

Now I appreciate the metal (some sort of titanium/aluminium alloy ?) will need coating and protecting, but a *choice* of colours.

Given the base cost is about £1,400, how much of that is it to have a choice of colours ?

Where's Henry Ford nowadays ?

[Brian Gaff]

Don't they also change the colour of the seat and othe bits to make it look nice?

Brian

[Nightjar]

If it is aluminium, the protection will be anodizing and colouring that is only a matter of adding a dye during the process. I don't recall that being significantly more expensive than plain anodizing when I used to have it done. The main problem I had was finding anybody who was using the colour I wanted at the time I needed it done.

ISTR that black is one of the more difficult colours to achieve with anodizing.

Colin Bignell

[Jethro_uk]

It's not the absolute cost ... I appreciate it has to be protected. It's the *additional* cost of having a production facility which caters for different colours ... surely there's an overhead from needing more space

- if just to store the material for additional colours.

[Andrew Gabriel]

Yes, it adds a bit to the cost of heat sinks, but it makes a significant difference over not being anodised. Most other colours work almost as well - it's just shiney natural aluminium which is bad at radiating.

I discovered by accident that it makes for a really good insulator too. When breadboarding a circuit which switches mains directly with mosfets, I temporarily fitted them to a heatsink with bulldog clips on the bench, and made a point of not touching the live heatsink.

It was only afterwards when disassembling them to use them in the final appliance (where I used proper insulated mounting kits) that it dawned on me the two mosfet mounting tabs had 240V mains across them, and it was relying on the insulating properties of the anodizing to prevent shorting out across the heatsink, oops. Good job the bulldog clips didn't scratch through it...

[polygonum]

Is it much better as a radiator than that dark, green-grey-ish yukky colour typical of hard anodised?

[Nightjar]

As a global organisation, Invacare probably just ships the parts from whichever country has the necessary facilities.

Colin Bignell

[Andrew Gabriel]

Emissivity of bare aluminium is less that 0.1 Emissivity of most dyes is 0.9 or better, i.e. a factor of 10 better. Varying the colour even right though to a perfect black-body emitter would only get you another 10% tops (and even black anodised aluminium isn't going to be a perfect black body emitter), so it's not very significant what colour you use as long as it's not bare aluminium.

Of course, you still have convection or forced air cooling - it's only the radiative cooling which is impacted, so it depends on the design of the thermal system.

[alan]

He didn't say you can any color as long as it black - he offered the model T in many colours.

[polygonum]

Regardless of reality, it is often suggested that he said "You can have any colour you like so long as it is black." And further, it is suggested that the reason for this was that black paint dried faster than other colours so kept the production line rolling as fast as possible.

Either or both the above may be true - or false. But they are commonly believed and repeated.

[meow2222]

Black was especially cheap & durable

[tim.....]

or more likely the stock of finished product in multiple colours

tim

[fred]

I'd guess their profit margin is plenty high to allow them offer the no cos t choice. Now if they were made by BMW....