what can be used to make cardboard shapes sandable etc?

[nick-a-tron]

hey eveyone. iv'e just built some cardboard mock-ups for a project but they turned out much nicer than i was expecting so was wondering if there was a certain product i could apply over the cardboard to hide the edges where it has been cut and where you can see the inside corrigation etc. also i want to be able to sand the corners to round them off a little. i was thinking about using something like bondo but its not really that kind of deal. i feel like i need to apply somesort of thin strips of something and use a liquid of somesort to work it into the corners and make it all sanable once its set. kind of like when you put fiberglass into a mold. any suggestions?

 

[motivealloy]

Elmers glue and strips of balsa wood would be my suggestion.

 

[nick-a-tron]

Elmers glue and strips of balsa wood would be my suggestion.

hmmm has to be something thin though. ive already got the shapes with the details on, just need to give them like a thin coat pf plastic so i can sand them and hide the cardboard edging etc. im thinking i need to dip very thin strips of material into something and then lay them onto the cardboard and work it into the detail so that i can sand it etc when it sets/drys. i just dont know what products would achieve this.

 

[Ti-el_terall]

Polyurethane resin?

 

[nick-a-tron]

can that be brushed on? i think what im trying to achieve here is a thin plastic coating to the cardboard. i have been looking at fiberglass sheets and seen that it's used on boat repair etc.

kind of like what is shown here (5th photo down)..

http://www.bigislandcanoes.com/pages/Canoe_page2/Canoe_page2.htm

can you get fiberglass sheets that are thin enough to use on props?

 

[Ti-el_terall]

Well polyurethane resin aka fibreglass resin, is what you brush on fibreglass. You probably would be fine doing a few coats of it on the cardboard.

 

[nick-a-tron]

Thanks!

 

[punisher]

you can buy spray on resin at any hobby store, like hobby lobby or michael's
its in a blue and white can and is about 4 bucks!

 

[weaselflinger]

I've used spackle for drywall with good results.

You could also brush on a couple layers of elmers glue.

 

[CustomCreations]

you can buy spray on resin at any hobby store, like hobby lobby or michael's
its in a blue and white can and is about 4 bucks!

really ? is it air drying then? Would like to know more, I havent heard of this ( Im in the UK)

 

[OB10]

If you were using a regular non-corrugated carboard, I could give you some good advice. A local RPFer has done some AMAZING things with cardboard, and has demonstrated some of his techniques.

BUT, here's a suggestion, and it'll work on corrugated or non-corrugated cardboard. Get Minwax Wood Hardener, from Menards, Walmart, Home Depot... It's with the wood dyes and stains. It's meant to be painted on rotting wood to stiffen it up, but it absorts into cardboard really well, too. Makes it sandable, paintable. After it dries, you should be able to use bondo or spot putty. If you wanted to use Durham's Water Putty or Elmers glue or something, you'd want to use that before doping it down with the Wood Hardener.

Make sure to use this stuff with good ventilation, and away from flames. It's chock full of all sorts of nasty, flammable chemicals. But the final results are pretty cool.

Obi-Bob

 

[dropshipbob]

Would wood putty work? I've used a brush-on material that is designed to fill in the grain so that you can sand it smooth.

Can't remember what it's specific name is.

 

[Snowflake]

If you were using a regular non-corrugated carboard, I could give you some good advice. A local RPFer has done some AMAZING things with cardboard, and has demonstrated some of his techniques.

BUT, here's a suggestion, and it'll work on corrugated or non-corrugated cardboard. Get Minwax Wood Hardener, from Menards, Walmart, Home Depot... It's with the wood dyes and stains. It's meant to be painted on rotting wood to stiffen it up, but it absorts into cardboard really well, too. Makes it sandable, paintable. After it dries, you should be able to use bondo or spot putty. If you wanted to use Durham's Water Putty or Elmers glue or something, you'd want to use that before doping it down with the Wood Hardener.

Make sure to use this stuff with good ventilation, and away from flames. It's chock full of all sorts of nasty, flammable chemicals. But the final results are pretty cool.

Obi-Bob

I think that's the way! Or you could just use Polyester resin (that's the one used fot fiberglassing, polyurethane resin is the one you use for rotocasting and siliconmold)... It's the technique used with Pepakura cardboard models, the resin absorbs into the cardboard pretty well making it sandable. And you could use some bondo to fill the corrugated spots.

 

[OB10]

The only wood putty I've used in a long, long time is Durham's. You mix water with the putty powder, and you can use if for.... an hour or two? (Been a long time since I've even used that.) But once it does harden and dry, it gets really, really hard. Even sanding it will take some time, so start rough sanding before if fully hardens. Although it gets really hard, if you drop or hit it hard enough, it'll crack. So don't hit it.

Not as familiar with normal putties or spackle, though. But I think that Durham's should suck up the Wood Hardener just fine. I doubt it would make it any harder, but there shouldn't be any conflict between the different materials as long as you add the Wood Hardener later.

Obi-Bob

 

[OB10]

I think that's the way! Or you could just use Polyester resin (that's the one used fot fiberglassing, polyurethane resin is the one you use for rotocasting and siliconmold)... It's the technique used with Pepakura cardboard models, the resin absorbs into the cardboard pretty well making it sandable. And you could use some bondo to fill the corrugated spots.

I've tried a number of different mixed media combos. I don't think I've ever done the polyester and cardboard. It seems like it should work really, really well. I'm just liking the way the Wood Hardener is readily available, and you don't have to mix it up, just use it straight out of the can! Might be fun to do a comparison between the two, see what advantage each technique has.

Obi-Bob

 

[RussellSculpts]

You can try apoxie resin, perfect for thin coat applications. Look it up through reynolds advanced materials out of orlando. gives it a good eggshell. May have to do several layers. not as stinky as polyester resin.

 

[Snowflake]

yeah polyester is cheap but it's a hell of a mess to work with! I tried it on cardboard for a pepakura model i made and it is a nice mix

 

[dropshipbob]

The only wood putty I've used in a long, long time is Durham's. You mix water with the putty powder, and you can use if for.... an hour or two? (Been a long time since I've even used that.) But once it does harden and dry, it gets really, really hard. Even sanding it will take some time, so start rough sanding before if fully hardens. Although it gets really hard, if you drop or hit it hard enough, it'll crack. So don't hit it.

Not as familiar with normal putties or spackle, though. But I think that Durham's should suck up the Wood Hardener just fine. I doubt it would make it any harder, but there shouldn't be any conflict between the different materials as long as you add the Wood Hardener later.

Obi-Bob

The stuff I used was like a thick syrup. Brush it on, let it dry and sand away.

 

[Ti-el_terall]

yeah polyester is cheap but it's a hell of a mess to work with! I tried it on cardboard for a pepakura model i made and it is a nice mix

Oops, spelling error on my part. I have made a few pepakura models and I find its not to bad to work with.

 

[FakeBritishAccent]

Good call on the drywall spackle...I finish that up with many many many many layers of primer dried between coats.

-Jonaas