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In depth idiot
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If this is to bond the foam sheet uniformly and strrongly onto the ply, then I suggest a spreadable adhesive is the right type. PVA will do the job on many foams like expanded polystyrene, but those that are waxy will need a solvent based 'impact' type. Further alternatives, Copydex, which is an easily spreadable latex solution, or a spray adhesive like my old friend 3M spraymount, or similar; these make a weaker bond, but are very quick and easy to apply very evenly.

Ask the foam supplier for any incompatabilities and recommendations, followed by testing at least 24 hours in advance of the intended use, to ensure no immediate degradation of the foam.

(It's a tricky field, I could cite many examples where manufacturers have 'done their research' yet some years later have faced customer claims because the foam has become hard and incompressible, or a soggy sludge, or a brittle substance crumbling into powder: sometimes all these results from nominally the same foam and adhesive combination. I was fortunate to know a chemist who served ICI Plastics Division as their chief analyst in the previouis century and his comment on such events was 'problematic, we are working in it'. There has been much progress since ...)
 

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I have a hot glue gun would that damage the foam???
Probably not unless the foam has a low melting point.
If it were me, I'd use PVA or Copydex. Copydex has the advantage that you can probably separate the foam and the ply later if something bad happened.

David
 
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C55
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Hi Babs,
You're right about the hot glue and foam. Fortunately, the foam has thousands of tiny pockets, just perfect for a liquid glue like PVA. Simple and inexpensive, it works really well. It works so well that it may be as well to use it sparingly, if it might be possible that alterations may happen at some later date. {Little pockets - think 3D Zipper or Velcro}

J
 

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Discussion Starter · #125 ·
Hi Julian I certainly prefer copydex as i am a frequent get it wronger :ROFLMAO: and comes of really well so you can do it again:love: love rolling the old copydex in my fingers at least that way it gets rid of the mess easily.
Babs
 

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Discussion Starter · #127 · (Edited)
Julian & Everyone The foam that i will be using is not what i call standard foam like insulation as it is extremley expensive to buy came accross this foam in 4 × 2 ft Sheets reasonable price bought 8 sheets and they sent them by courier. We have made a template for the hot blade to go through should be fun. Just need a dry day. As it smells horribly when cutting..
Babs
 

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C55
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Interesting looking, I can't recall seeing anything quite like it, before. The reason I asked , is because the normal closed cell stuff [crumbles into little balls of foam when cut or broken - hence closed cell description] , is normally a bit of a fire risk. It adds to any fire that may be started elsewhere, burning very vigorously, I can't see that being a massive problem, to be honest, given some other materials we model with.

However, it also doesn't like wiring insulation, reacting with it to break it down and resulting shorts can set it off, under it's own steam. It is possible to run wiring through simple ducting, to keep it separate, where it runs adjacent, so it certainly isn't insurmountable, but well worth checking in advance.

Not having seen the boards you have got, I can't say either way, for sure. It may be worth taking a look to see what their label says on fire resistance. It should also be possible to Google their name for the "type" of foam board and see the full spec there.

Best wishes
Julian
 

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Discussion Starter · #129 ·
Julian Thanks for that very important info. I have already thought of the fire risk. And bought some miniture conduit for that purpose but to be honest there will not be many wires in those sections.
Babs
 

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C55
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Oh good, you are way ahead of me and well sorted. (y)

There have been a number of comments on the subject and probably rightly so, as a caution. I'm not completely sure of how high the risk is. Reports of actual fires seem to have passed me by, as I have seen precious few and were caught at the stage, of fumes passing the nose, giving rise to the layout being shut down and then sorted. Still, it's best dealt with as you already have, for easy nights sleep. :coffee:

J
 

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Discussion Starter · #133 ·
Good Afternoon Everyone. Bought this tool from ( Farnels ) Some months ago hot blade cutter for cutting foam Very impresive indeed it was just under £25.00 and it cuts the foam like butter. There was some nasty smells but masks were worn . ( Dont do it inside )Just Amazing indeed
Babs
 

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