Need a tech tip for custom designed seats.

[Andrew]

Has anyone had experience with a type of 2 part liquid foam material?
I have seen a number of custom car and motorcycle shows that show a product that can be mixed together to produce new inner seat cushions. When mixed the product begins to cure and expand producing a high quality foam material good for seats or similar products.
Andrew

 

[Green67Alpine]

We use a product like that to ship parts in, Seat cushion foam most be a combo of similar chemicals. The packaging foam would never last in a seat cushion(very long), but it's great for filling voids that don't get wet. Remember the guys that are demo-ing that stuff have had LOTS of practice, it will eventually wear off your skin, anything else, it's pretty much permanent.

Tom j

Still trying to adjust those wonderful Stromberg carbs !!

 

[miket]

I would imagine that you could get foam blocks at a home decoration center or one that sell cushion material. We have them here, you must too.

On american hot rod they used an electric knife to shape the cushions.

 

[Andrew]

Hi Miket:
Yes, high density foam works well. It is also possible to use a wire wheel to cut away bits if you don’t have a knife.
I found a company that offers expanding foam but it is not cost efficient.
So the high density is the way to go.
Thanks a bunch,
Andrew

 

[64beam]

Hi Andrew,

A better way to cut your foam would be to make yourself a hot knife (very easy to make using some wire and descent battery). Just a thought.

Regards, Robin.

 

[WaltSV]

A hot knife will only work with polystyrene and polyethylene foams (like the two types of white cushion packaging foams). For urethanes (yellow), some cutting action is typically necessary.

An electric slicer is what the pros use. Utility knives, long serrated knives are also useful.

Depending on density / rigity abraisives are also effective.

Walt
Seattle

 

[Nickodell]

Thanks for the input. Another thing to remember is that polyurethanes give off various toxic gases (e.g. cyanide) when heated. It's not a good idea to breathe polystyrene fumes, either. Polyethylene is pretty innocuous.

 

[WaltSV]

Thanks for the input. Another thing to remember is that polyurethanes give off various toxic gases (e.g. cyanide) when heated. It's not a good idea to breathe polystyrene fumes, either. Polyethylene is pretty innocuous.

Generally speaking, the residual gas from any foam plastic is unhealthy to breathe, similarly to inhaling smoke from a wood fire, low O2, high CO content.

Unlikely that any foams produced domestically in the last few decades will have any otherwise lethal gas released from heating, vintage foams may be a diferent story. Certainly that is the case with foams designed for consumer use as in building construction and upholstery, maybe not for packaging or industrial applications.

The solids in the smoke are probably more harmful long term.

Walt

 

[Nickodell]

Walt, while I agree about the "gassing-out" from foams having improved in recent years, you are incorrect about the effects of melting and burning. Polyethylene [ (C2H4)n ] is not really a hazard as it is a hydrocarbon chemically almost identical to paraffin wax [CxH2x+2, where x is any number higher than about 20.] If you burn a small piece you get an odor similar to that of a candle, and the same kind of yellow flame. The EPA and OSHA rate fumes from burning polyethylene an "irritant," but not toxic.

Polystyrene can be incinerated safely using the proper equipment, but when burned haphazardly can release toxic fumes. Burning polystyrene produces an evil-looking, sooty flame, with lots of red. When cut with a hot wire, it can depolymerize to release styrene, a carcinogen.

Unlike the other two, the polyurethane molecule contains nitrogen, and burning PU of any vintage produces carbon monoxide and hydrocyanic acid (HCN), AKA prussic acid, both of which can kill you by the same means (HCN in a minute, CO takes longer), preventing the red blood corpuscles from carrying oxygen. As a result, fumes from burning chairs, couches etc. are one of the principal causes of "death by smoke inhalation" in house and office fires.

 

[WaltSV]

Fire is an extremely complex and chaotic process. Products of combustion for any material can be remarkably varied and for the most part, hazardous. Even polyethylene. So all of these materials (indeed, virtually all materials that burn) produce toxic compounds which can be very hazardous. When talking about fire, it is often best to consider comparisons with common materials. Cotton, leather, and wool all produce very toxic gasses (worse than any of these plastics), yet are considered "natural" and safe to use.

Comparing the combustion products of plastics, as you know, is a dangerous strategy. Most people recoil at any mention of toxins or poison and the danger is that rationality will fall by the wayside and the customer will end up eschewing all plastic products.

This having been said, the point is that that all materials that burn produce toxic compounds, the fire environment is more important (in many cases) than the material that is burning (a slow smolder differs from a roiling flame), and that all burning materials should be considered as producing toxic gases.

Whether it's C0 or the cyanide present in many organic smoking materials, dead is dead. Given the choice, I guess I'd choose custom leather seats over the couch.

Walt

 

[Green67Alpine]

Whether it's C0 or the cyanide present in many organic smoking materials, dead is dead. Given the choice, I guess I'd choose custom leather seats over the couch.

Walt

At least you'd be stylin'

Tom j