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Techniques for making foam bag seat ?


ECR

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I know the basic principles but am after any "tricks of the trade". For instance is it best to cast the seat in more than one go (3 ?) in order to get the seat area fully filled first and then the back rest? I assume that you use blocks in order to create your preferred position and then foam round the holes created as a final operation ? Any tips would be helpfull
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I've always done it in two parts, seat base and then back. Two tips, when you mix the two ingredients together, the foam starts very quickly. Make sure you're sitting in the car with someone else pouring the foam. The second tip is put some old overalls on. If you put too much foam in it goes everywhere.
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Chemical reaction is temperature sensitive- needs less mixture in high temperatures, also exothermic developing heat whilst foaming & curing.

 

Take care, sticks well - to most things, and if it is the same stuff I used to build in buoyancy in canoes then the fumes are bad for you.

 

So, tempting to save mixture by having a nice warm snug garage, but don't, ensure there is good ventilation. However having the cans of two part chemicals at a warm room temperature will speed things up (reaction is fairly fast anyway).

 

Regards,

 

allen

 

PS. Let us know how it went.

 

Edited by - allen on 19 Sep 2001 17:01:10

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Instructions ?? Wot they then ???!

 

I guess some experimentation will be required - I've got about 2 litres of each chemical so I've got some spare for "mistakes".

 

You can get the chemicals from Glassplies. If I can find the number I'll stick it on here but Yellow Pages should have it.

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"The first lot cost more than twice as much from Demon Tweeks!!"

 

Now there's a surprise.....

 

Glass plies were pretty reasonable - I got something like 2 1/2 litres of each chemical for about £35. Enough to make two seats including experimental prototypes.

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ERC

 

Click here for foam website.

 

I got 2.5l and it mas more than enough to do a seat with no extra padding.

 

Tips:

 

Have lots of suitable containers for mixing. We used 4l plastic milk bottles with the top cut off.

 

Measure out 3/4" to 1" of each fluid. Stir well and pour into a bin bag in car. For the base a pizza sized blob is about right. As this starts to foam get in.

 

Get the basic shape right by using some sort of back support. After the foam sets you can get out and then put in smaller amounts to fill out the gaps, sitting back in each time. Once fully set a wood saw is the best for trimming.

 

Repeat for the seat back.

 

All the warnings about mess and stickyness are true! I've the overalls to prove it. blush.gif

 

Matt

 

 

 

Is it a bike? Is it a car? No it's Blackbirdman cool.gif

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One other tip, Dont wory when its finished if you have a few gaps and holes in the seat, as all you need to do is make up a very small amout and ladel it directly into the gaps/holes with a teaspoon then watch with satisfaction as it expands to fill the gaps. Finish by hand with a surform or sander, but wear a mask.
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  • 3 months later...

I have bought some of this foam, and am starting to think it was a bad idea. I have visions of a Frank Spencer esque scene.

 

Stupid question time.

 

1. I leave the top of the bin liner un fastened - right?

 

So if I put too much mixture in it will spew over the top and make a huge mess???

 

2. Can I put the foam directly onto the ali floor, or should i put a piece of thin plywood in first?

 

3. Less stupid question - any bright ideas other than tank tape for upholstering the foam? I was thinking of spraying with glue and then using a stretchy vinyl.

 

Sara is planning to video the process with a view to an appearance on one of these domestic disaster video shows.

 

best wihes for the new year

 

 

Jonathan

 

 

 

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1. I leave the top of the bin liner un fastened - right?

 

It does expand and gets very hot. Leave some space for expansion but close up the end of the bag

 

So if I put too much mixture in it will spew over the top and make a huge mess???

 

Yes

 

2. Can I put the foam directly onto the ali floor, or should i put a piece of thin plywood in first?

 

Not a good idea. THe wet mix is very sticky and will be very difficult to clean up if it gets on the wrong surface.

 

3. Less stupid question - any bright ideas other than tank tape for upholstering the foam? I was thinking of spraying with glue and then using a stretchy vinyl.

 

 

I took mine to the local car upholsterer and he did a squab covering in leather for around 40 quid.

 

Andrew

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Maybe thios is what Suzi is expecting ...... its cut & pasted from Mike Bees reply last year , always makes me laugh ...

 

And this is how not to do it:

 

----------------------------------------------------------

 

A friend of mine once built a canoe. He spent a long time on it and it was a work of art.

 

Almost the final phase was to fill both ends with polyureathane expanding foam.

 

He duly ordered the bits from Mr Glasplies (an excellent purveyor of all things fibreglass) and it arrived in two packs covered with appropriately dire warnings about expansion ratios and some very good notes on how to use it.

 

Unfortunately he had a degree, worse still two of them. One was in Chemistry, so the instructions got thrown away and the other in something mathematical because in a few minutes he was merrily calculating the volume of his craft to many decimal places and the guidelines got binned as well.

 

He propped the canoe up on one end, got a huge tin, carefully measured the calculated amounts of glop, mixed them and quickly poured the mixture in the end of the canoe (The two pack expands very rapidly).

 

I arrived as he was completing this and I looked in to see the end chamber over half full of something Cawdors Witches would have been proud of. Two thing occurred to me, one was the label which said in big letters "Caution - expansion ratio 50:1" (or something similar) and the other that the now empty tins said "approximately enough for 20 small craft."

 

Any comment was drowned out by a sea of yellow brown foam suddenly pouring out of the middle of the canoe and the end of the canoe bursting open. My friend screamed and leapt at his pride and joy which was knocked to the ground as he started trying to bale handfuls of this stuff out with his hands.

 

Knocking the craft over allowed the still liquid and not yet fully expanded foam to flow to the other end of the canoe where it expanded and shattered that end as well.

 

A few seconds later and we had a canoe with two exploded ends, a mountain of solid foam about 4ft high growing out of the middle, and a chemist firmly embedded up to his armpits in it.

 

At this stage he discovered the reaction was exothermic and his hands and arms were getting very hot indeed. Running about in small circles in a confined space while glued to the remains of a fairly large canoe proved ineffective so he resorted to screaming a bit instead.

 

Fortunately a Kukri was to hand so I attacked the foam around his hands with some enthusiasm. The process was hindered by the noise he was making and the fact he was trying to escape while still attached to the canoe.

 

Eventually I managed to hack out a lump of foam still including most of his arms and hands. Unfortunately my tears of laughter were not helping as they accelerated the foam setting.

 

Seeking medical help was obviously out of the question, the embarrassment of having to explain his occupation (Chief Research Chemist at a major petrochemical organisation) would simply never have been lived down. Several hours and much acrimony later we had removed sufficient foam (and much hair) to allow him to move again.

 

However he still looked something like a failed audition for Quasimodo with red burns on his arms and expanded blobs of foam sticking everywhere. My comment that the scalding simple made the hairs the foam was sticking to come out easier was not met with the enthusiasm I felt it deserved.

 

I forgot to add that in retrospect rather unwisely he had set out to do this deed in the hallway of his house (the only place he later explained with sufficient headroom for the canoe - achieved by poking it up the stairwell.

 

Having extricated him we now were faced with the problem of a canoe construction kit embedded in a still gurgling block of foam which was now irrevocably bonded to the hall and stairs carpet as well as several banister rails and quite a lot of wallpaper.

 

At this point his wife and her mother came back from shopping......

 

Oh yes - and he had been wearing the pullover Mum in law had knitted him for his birthday the week before.

 

----------------------------------------------------

 

Mike

 

[;E]teeth.gifteeth.gifteeth.gifteeth.gifteeth.gifteeth.gifteeth.gifteeth.gifteeth.gif

 

Edited by - Dave J on 31 Dec 2001 16:20:17

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Jonathan,

 

Mix up small amounts, Blackbirdman is right.

 

Plan the operation, lay stuff out ready (containers, stirring sticks etc.) and go for it. Once it starts foaming you can't stop it.

 

Wear old clothes and rubber gloves. I would probably cover the floor and tunnel and seat back bulkhead in polythene as well as putting the mix in a bin liner. However, a layer of vaseline will also stop it adhering.

 

Good luck

 

allen

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Arrowstar did my seat about 5 years ago and it's been excellent.

 

It's in two parts, the squab and a back rest, this makes it much easier to remove from the car. The squab was made first then roughly trimmed to shape, the trimming incorporated what I can only describe as a tongue on the back, the back rest was then formed in another bag resting on this base at the bottom so naturally incorporated a groove. Hey presto a tongue and groove joint between the two bits. More difficult to describe than do I'm afraid.

 

The squab incorporates a small square of high density rubber matting, about 200mm square that I actually sit on, similar density to those camping mats, about 15mm thick. This was placed in the bin bag before I sat in the car, I sat on this bit of mat, it only needs to be under the bony bit of your buttocks (technical term???). When the foam was poured in it moulded itself around this bit of matting which is now irretrievably part of the seat.

 

The foam doesn't go straight on the ally panels as it's in a bin bag, is that what you meant, there's no plywood, the seat sits straight on the floor.

 

Mine was covered professionally by an uphosterer that Arrowstar knew, looks very nice and has lasted well but it cost more to do this than make the seat.

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Mikes is a wonderful story. A mate of mine was once a policeman and he got called to a revenge attack on someones house for an unpaid debt, where someone had poured, what the forensic guys reckoned to be 10 litres of the stuff, through the householders letterbox overnight and completely filled the hallway of the house with it. He said it was one of the most memerable things he took away from the job.
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Steve,

 

In response to your question:

 

"Has anyone made a bag seat that can be used with the rear part of a bench seat?"

 

Yes, I did this although is was a moulded base in conjunction with an S-type seat.

 

This means that I can swap between the Leather seat base and my moulded one as required.

 

I used a polystyrene kit rather than the expanding foam. Much more expensive but far easier to work with.

 

I could send you photos if you are interested.

 

Peter

 

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