Thin, soft foam from where please?

[T i m]

Hi All,

A while back I asked if anyone could point me in the right direction of some thin foam to be able to refurbish the heater on our MkII Escort based kit car.

The original foam looked like it was black, about ~3mm thick and was very soft / compliant (I could only see this from the few bits that remained and that weren't all hard / crispy). I think it was also 'open cell' foam from what I have tested so far.

Everything I have considered so far has been either too thick (upholstery foam (min 6mm?)) or too dense (neoprene) and so not allowing the fairly light,, lightly sprung and uneven edged metal 'flaps' within the heater to seat properly. It doesn't need to seal against any real air pressure as such, just resist air flow, so you don't get hot air leaking though in the summer etc.

FWIW, I just had some refurb cartridges delivered for my (Freecycle ) colour laser printer and the plastic protectors that cover the output roller came with what may be the nearest I've seen to what I need so far, all be it a bit thick at 6mm (probably 'low density upholstery foam').

So, it would need to be about 25mm wide (strips or cut from a sheet), ideally ~3mmm thick but (and this seem to be the biggie ... ) very soft / compliant ... such that if you pinch it between your fingers there is little or no resistance? I would also prefer it NOT to be self-adhesive as I have no idea how the supplied adhesive may cope with the hot // cold. The ultimate solution might also be fuel, solvent and fire resistant but that may be hoping for too much. ;-(

I have tried in haberdashers, had samples of window sealing / wetsuit foam sent from eBay and other suppliers but still not found anything suitable.

I'm asking here because I know you can often come up with good 'outside the (heater) box' ideas. ;-)

Cheers, T i m

[Bertie Doe]

Hi All,

This is 2mm thick :-

[T i m]

Thanks for the feedback but I think that stuff may be way too dense for this application. It says it's made from 'closed cell polyethylene' and is that 'waxy' foam you sometimes get with motherboards (possibly an anti-static version).

Cheers, T i m

[Tim Lamb]

In message , T i m writes

Is this a Vauxhall Zafira pyrotechnic in the making?

I have roll of left over hardwood flooring underlay which might suit. About 3mm with a polythene backing.

[alan_m]

Anti-static foam from on-line eletronic retailers?

[alan_m]

Or from any shop building computers etc. Used to pack the components they use.

[T i m]

Could be. ;-)

Of a very soft foam Tim?

How well do you think that would take heat (within a car heater)? Or do you think it could be separated?

Cheers, T i m

[T i m]

Yup, that could be an avenue worth pursuing ...

That looks good but the thinnest they do is 6mm. That could be ok IF it's very very soft, such that a thin metal flap could compress it around it's entire perimeter.

I'm good friends with a shop that builds computers and I'm not aware if him having anything suitable. That said, I *have* seen some thin open cell foam under / with pcbs but not for a while or necessarily big enough without doing a bit of patchwork (which I can do if push comes to shove). ;-)

Cheers, T i m

[Tim Lamb]

In message , T i m writes

Pass and pass again. It is intended to withstand underfloor heating temps. so 50 deg. C or so.

Mail addy works. I can easily stick a bit in an A5 envelope.

[Jonno]

T i m scribbled

This ?

#post2709999

[T i m]

Ok. I know the stat / fan switch on the kitcar are around 95 DegC so there is a good chance it could reach those sorts of temps inside the heater box?

You are very kind thanks. Following the antistatic foam thought I came across some 1/8" carbon foam and that in turn took me to carbon filter foam as used in cooker hoods. I've asked the seller to confirm the thickness and density but I may have to buy some to be sure. Being open cell (filter material) and 'fire retardant' means it might be suitable and from the pictures I've seen on the net and looks very similar to what I found in the heater before I refurbished it (mainly to clean out the matrix but also to replace the blower motor for one from a motorcycle cooling fan as the plain oilite bearings had gone on the original).

Thanks again ... T i m

[The Natural Philosopher]

should do what you want.

[T i m]

Thanks for that TNP. They certainly do the right thickness but I think even the low density stuff is going to be too springy.

The test would be, take a 12" rule and gently push the edge down on the foam and see how much the foam 'gives'. With the neoprene(s) I've tried so far the rule wouldn't move at all, whereas with the 'right' density it would flatten the entire length down to (or very close to) the supporting surface.

It has to be that compliant because the 90 deg folded edges on the thin steel flaps aren't particularly even and could easily differ in flatness by 3mm across the entire flap. This would mean that with any foam of any noticeable density, there would be some fairly large gaps for the (say) hot air to blow out during the summer. ;-(

Do you have a cooker hood that uses a thin carbon filter foam that you could measure the thickness of by any chance please?

Cheers, T i m

[The Natural Philosopher]

oh. do you want foam strip???

nope :()

try also:

[T i m]

Thanks for looking but no, I've already got one of those waiting to go on when I rebuild and refit the heater. ;-)

Inside the heater itself are a couple of metal flaps that control hot / cold and up / down outlets. These are just fairly thin steel sheet with the edges turned over 90 degrees to form a short 'edge' and they pivot on one edge on a rod that goes right through the heater box. On the end of each rod is a short arm and that connects via a push-pull wire linkage to the dash mounted controls.

So, when the flap is moved to it's closed position, the edge is pressed onto a foam border and because there isn't a particularly heavy spring pressure on any of it, the foam needs to be pretty thin and light to allow the flap to actually seat. Further, if the sealing foam is too stiff / thick near the hinge, the flap won't even close properly. ;-(

So, whilst it's a pretty crude / basic setup, this foam really has to be something quite specific for the heater to stand a chance of working properly.

Cheers, T i m

[Tim Lamb]

In message , T i m writes

Well found.

[T i m]

Thanks for pointing me in that general direction. ;-)

This actually says just how thick it is but I can only seem to find it in the States:

Mind you, I don't care where it has to come from as long as the (total) price is ok. ;-) [1]

Cheers, T i m

[1] Well, I'd prefer to be able to get it locally but if I can't ...

[T i m]

Well, whilst strip would be useable, sheet would be better as I could then cut out a continuous 'frame' to match the outline of the flap(s), rather than having to create one with four separate sections.

Thanks for that. This looks interesting, IF it's compliant enough (and the 'skin' may make it less so):

I'll see if I can get a sample of the 3x16 strip. I can glue it on with silicone that I know will cope with the temperature ranges (I don't know the characteristics of any 'self adhesive' offerings).

Thanks. ;-)

Thanks for that and I may have already emailed or rung them and possibly even been sent a sample of the best they can offer. Again, the issue seems to be finding something thin enough that is also compliant enough (you can do one or the other but not both so easily).

I'm still hopeful the 1/8" thick, open cell, carbon foam may be the answer and from what I can see so far, looks exactly the same as what I think the foam on the Escort heater once was.

(That I'm hoping might be the same thing as cooker hood foam) ;-)

Cheers (again), T i m

[The Natural Philosopher]

The trouble with open cell foam is it wont seal worth a damn.

[T i m]

Agreed, however, if I find the right stuff, where the edge of the flap is compressing the foam flat, it isn't open cell as such?

Where it doesn't actually squash it completely flat it will still offer more resistance to general air flow (there is no real pressure as such) than something that doesn't compress at_all, leaving real clear gaps all around?

I would *love* to find some closed cell foam with the right characteristics ...

Cheers, T i m