Sintra Painting Help!

[Cinobite]

Firstly, awesome website, I've been reading bits for years, baffled by "vacuum molds" and "fiberglass construction", expecting things like commercial grade molds and sold fiberglass (like a canoe) I never got around to making anything.

Then last week I discovered Sintra! Not only that, it turns out I have been using 6ft panels of sintra for work (under "foamex"), which I through out every through months as they get replaced - I have a garage full off sheets of sintra!

And I love it!

So, I thought I'd try making something, this is my first "proper" build, I'm making the Aliens Colonial Marines armour, but I'm having trouble with the spray paint.
It just wont stick well to cut and sanded areas. Any ideas? It looks a bit messy other wise.

Any tips would be much appreciated, thanks! (pic attached)

 

[Iggy]

It looks like it is sticking, but that is just the finish. What you probably need to do is some cleanup on those edges. Use filler to clean them up and sand fine. Right now they are rough, and spray paint, will look rough as well.

 

[Cinobite]

Thank you for the reply.

I think you're right, I've just gone out and bought some super fine paper and some primer (I didn't even prime it).

To be perfectly honest with you, this was actually a "wow sintra, oh wow I have a garage full of that!, let's just try it out and see what it's all about", that has gone MUCH better than I ever expected! Hence the messy workmanship

 

[superjedi]

I'd agree that it's the surface and not the paint. I've used Sintra in some scratchbuilding projects and
I've always found that it behaves pretty much like styrene as far as adhesives and paint are concerned.
You should get a much better result once it's sanded smooth.

 

[Pro Mod]

You've just broken through the front skin and exposed the foam interior thats all.
If your material is Foamex are you in the UK? - if so prime it with Halfords acrylic primer and you can coat it with anything you like.

 

[CLOTHAR]

Also, be sure to use a respirator if you are sanding it. I think it contains formaldehyde and some other nasties, so that fine dust is not good to be breathing in.

 

[Cinobite]

Thanks. So I sanded it down with a 400 grade and it's much better - even primed it The only "messy" parts are now are some tiny places where the 2 layers of 3mm Sintra haven't bonded to the edge, but that's fixable/hidable with painting

For work I order "foamex". I checked with the company to see if it's Sintra, they never heard of Sintra (despite being a signage company) and said they know it as SmartX. I looked up the two from the creators and what I have seems to have more in common with Sintra than SmartX, so I'm going with Sintra. I use a standard mask when sanding and moulding although trying to get a mate to source me a fume mask as, from what I understand, it releases Chlorine Gas when heated.

 

[Cinobite]

Oh wow yeah, I gave the primer a light sanding and it's fantastic! I always knew you "should" prime and sand, but you know - all the extra work and that
Now it's almost as smooth as glass, you can't even tell there's 2 sheets stuck together

 

[superjedi]

Looks great. :thumbsup

For what it's worth Sintra is a brand name for this kind of material. It's "expanded PVC" and it's
sold under several names by several manufacturers.

 

[yaris]

foamex, celuka and sintra are brand names of foam pvc or expanded pvc, like perspex is a brand of acrylic sheet.

foamex is cooked longer than sintra, so it's a harder finish in smaller thicknesses.

ultimately is the primer that is key to adhesion. Acrylic laquer based primers work best, because they thinner melts into the surface instead of sitting on top like an enamel, minerla based primer.

 

[Cinobite]

Thanks again.

What should I use as an affordable, non gloss sealant after I've spray painted? I've read lacquer but I imagine that to be far too shiny and glossy for marines armour

 

[Pro Mod]

Unless you have a particular reason to overspray the paint it dosen't need lacquering. A matt or satin varnish will mark just as easily as the paint.
Vallejo produce matt , satin and gloss finishes which are very good https://www.amazon.co.uk/Vallejo-400ml-Acrylic-Varnish-Spray/dp/B000R9QHWO

 

[Cinobite]

What I've down is wiped it all over (after painting) with "weathering powder" solution, it's this that I think could do with fixing

 

[Pro Mod]

If it's a loose material that rubs of easily then spraying a sealer over the top of it makes sense.

 

[Psicorp7]

Yeah, if you are heating and sanding sintra, get a fume mask. That stuff is nasty when heated. The armor looks great, by the way!

 

[Spectre80]

Sintra is a pvc composite that needs to be primed with the proper product for any type of paint to stick to it. That product is called ti-bond. It is a clear substance that you spray with a hvlp spray gun, and yes, use a respirator. You want to lightly mist the sintra. Let it flash than apply first coat of paint. I use to work in the sign industry, if you have any more questions concerning an industrial paint application. Also, ti-bond may be purchased through an automotive paint vendor like ppg or Matthews paint.

 

[mdb]

foamex, celuka and sintra are brand names of foam pvc or expanded pvc, like perspex is a brand of acrylic sheet.

foamex is cooked longer than sintra, so it's a harder finish in smaller thicknesses.

ultimately is the primer that is key to adhesion. Acrylic laquer based primers work best, because they thinner melts into the surface instead of sitting on top like an enamel, minerla based primer.

Thank you I learned something about the baking times Nice to know that my experience with different surface hardness wasn't just imaginary! I have found thick sheets of Forex here tend to be very spongey once the surface has been cut and very prone to absorbing liquid (in a damp climate like I live it it is very noticeable), it definitely needs sealing.

ANd yes, acrylic lacquer for the win!
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