Painting high density foam.

[chrisonord]

I am not sure if this is in the right place or has been talked about before, if I am asking in the wrong place can the powers that be please point me in the right direction.
I have bought some high density foam to have a go at making something with it, I have seen some aircraft done with this stuff before, so thought I would have a go. Can anyone tell me what to use to seal it so I can paint it, or does it paint easily. I didn't think it would be easy to paint after looking at it closely.
Cheers
Chris.

[Mossie]

Not sure about polyurethane, but PVA might be possible. I bought some extruded polystyrene/Styrofoam (roof insulation foam) for a project, you can prime it with PVA.

It's also possible to use polyester resin for a very smooth finish.  This blog gives some tips, it mostly focuses on XPS but breifly mentions polyurethane and might help:
https://davidneat.wordpress.com/styrofoam/

[chrisonord]

Cheers mossie, I have seen that it can be glued together with wood glue which is virtually pva glue, I will give some a try on a small piece, and see if it is smooth enough.
Cheers
Chris

[rickshaw]

Acrylics or water colours are the only suitable paints to use.  Enamels have solvents in them which eat the foam.

How do I know?  From long experience making wargames scenery from expanded polystyrene foam.   

[chrisonord]

Oops...
I think water based everything will be the way to go with all gluing and painting, it's all going to be a learning curve for me
Chris

[kerick]

Yeah, anything with petroleum solvent will dissolve the foam. Water based is the way to go. Coat it with the PVA glue and be prepared to let it dry over night.

[NARSES2]

Yup, I've only ever used it for wargames scenery/buildings and only used posted paint after sealing it with PVA

[zenrat]

I once tried to use an expanded polystyrene coffee cup to transfer petrol from my motorbike to the fire I was trying to start.  That was a learning experience...

[Mossie]

For gluing, try UHU Por, it's made for foams, you can find it in a lot of places.  Grabs foams better than PVA, I've used it for kids projects. Copydex and fabric glues work well too.

In the blog I posted, gorilla glue has a particular advantage.  If you happen dampen the surface, it foams and if you tape the pieces together, it self fills and can be cut and sanded like the foam itself.  I've yet to try this myself though.

EDIT, Cheers Fred, dangers of typing on smartphone.  I at least spotted what the predictive text turned "Por" into....

[zenrat]

I think you may have meant to type dampen.

[chrisonord]

Thanks for the info and advice folks, really appreciated
Chris

[kerick]

I once tried to use an expanded polystyrene coffee cup to transfer petrol from my motorbike to the fire I was trying to start.  That was a learning experience...

That's a trick played on the new guy in every shop that uses petroleum solvents!

[jcf]

CA glues for foam are a available, the RC guys use it a lot.

[NARSES2]

I once tried to use an expanded polystyrene coffee cup to transfer petrol from my motorbike to the fire I was trying to start.  That was a learning experience...

Should you be posting that here ? Or do Australian States have a Statute of Limitations, unlike the U.K. ? 

[zenrat]

I once tried to use an expanded polystyrene coffee cup to transfer petrol from my motorbike to the fire I was trying to start.  That was a learning experience...

Should you be posting that here ? Or do Australian States have a Statute of Limitations, unlike the U.K. ? 

I was in the UK when trying to do it.  At Sompting* Cricket Club IIRC.

* Just down the road from what was once Ford Airfield from where the FAA flew Wyverns.