Insulating paints?

Posted on July 28th, 2008 in Driving Emotion,Intercooling,Technologies by Julian Edgar

Whenever talk turns to intercooler colour, two schools of thought emerge. There are those who suggest intercoolers should be painted black to aid heat dissipation. Then there are those who suggest the insulating properties of paint would outweigh any better thermal emissivity the intercooler would gain with its colour change.

I have always thought – and continue to think – that the insulating properties of a very thin layer of paint would be effectively nil. After all, you don’t have much faith in that ‘insulation’ when you’re reluctant to put your hand on a painted exhaust manifold or exhaust pipe!

But what about paints that are designed to insulate? Clearly you wouldn’t put them on an intercooler – but what about the pipe coming back from the intercooler to the inlet manifold? As I wrote in Insulating the Return, measurable gains can be made if engine bay heat is prevented from warming the returning air.

At least two different approaches are taken to insulating paints. The first is where the special paint is bought and simply applied. The other approach is where you mix an additive in an existing paint.

InsulTec is an example of the premixed stuff. The applied paint is apparently so thick that the maker calls it a membrane, rather than just paint.

Insuladd takes the additive approach. The additive comprises tiny ceramic ‘microspheres’ – they’re so small the additive looks like flour. To reduce cabin temperatures, apparently at least one local race car team is using the additive in the paint they put on the firewall.

It all sounds like it could work but clearly the vast majority of experience has been gained on the roofs of buildings. In that application, where the incoming radiation is short wavelength, different aspects of the paint (like its colour) may be more important than the composition of the stuff.

I dunno. But I’d be curious to hear from anyone who has used insulating paint in an automotive application – irrespective of whether it was a success or failure.

5 Responses to 'Insulating paints?'

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  1. Henri said,

    on July 29th, 2008 at 3:01 am

    Julian, I live on the coast of the Gulf Of Mexico and it gets to 95F here quite frequently in our summer. Bought a Dodge maxivan originally painted lite blue, and repainted the van roof with 5 layers of Kool White (with a brush!), which is a latex based roof paint for metal roofs of mobile homes and the like. Using household thermometer probe, in the summer the roof temp was reduced about 40F in early afternoon, and I survive quite nicely with NO air conditioning. Very Impressed. One negative, its relatively porous and collects grease from your hands. Secondly, its very flat. Maybe not for a show vehicle, but very effective on a utilitarian vehicle. This paint seems to have some thermal barrier properties and may have a measurable benefit on a firewall. Note that all schoolbuses in the Southern US seem to have white roofs.

  2. stewart said,

    on July 29th, 2008 at 7:40 am

    Why not just anodise your intercooler black?

  3. Monty said,

    on July 29th, 2008 at 3:12 pm

    AFAIK the microspheres promoted for use as a paint additive are similar if not the same as microspheres used in fiberglass boat building as a thickener for epoxy resins. The biggest difference is probably the price! Boatbuilders get their spheres significantly cheaper.

  4. Michael said,

    on July 29th, 2008 at 5:07 pm

    what about your results with your gtr intercooler julian, i always found them interesting…

  5. on August 22nd, 2010 at 6:26 am

    It seems that Insulation Paints have been discussed for a long time now. Have you noticed any changes since 2008 regarding insulation paints in general?