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finishing styrofoam?

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cls

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hi TRF,

on a recent rocket project, is one of those open-cell styrofoam balls. (see picture below)

I want to put a pretty nice finish on it, something smooth, that will also hopefully keep it from crumbling.

we've tried poster paints but they don't really protect that kind of foam.

maybe a coat of epoxy? (not polyester!)

thanks!
 

rstaff3

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When I have used that type of foam, I filled it with fill-n-finish and then gave it one layer of glass.

BTW is that a Cognis Lander?
 

cls

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thanks rstaff3, I will try fill-n-finish. dunno about glassing it, I am concerned about weight.

yes it is a cognis lander!! I started another thread in the Kit Reviews section about it.


Man, I love TRF! quick and right-on!!
 

rstaff3

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Unfortunately even fill-n-finish might get heavy since the foam cells are so open.
 

Habu

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I did something similar a few years back.
I used lightweight spackle then sanded and primed with latex base primer. After all that was completely dry I proceded as per normal (for me anyway) with rattle can auto primer and Krylon.
Worked for me.
Your milage may vary...
 

rstaff3

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The light weight spackle is an excellent idea for this application.
 

cls

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what brand of "lightweight spackle"??

thanks!
 

Missileman

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They beat me to the punch, Yes light weight spackle.
I use DAP myself. Bought a tub at Miejer's for about 3 bucks.
You may have to mix just a little water with it to get the right consistancy.
 

Micromeister

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over Styrofoam Mod-Podge is a good choice, you can use the stuff over Jap tissue, or even that thin white wrapping tissue. once the stuff dries it will accept regular primers without effecting the foam underneath.
The Big Point below is covered using this method.
 

gerbs4me

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I use Elmer's glue all, just put a couple light coats on, but it still will have a textured feel, I usually glass it, since weight is an issue couldn't you just add resin?
 

cls

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Gerbs, interesting idea to glass it. I didn't want to try glassing it because the fiberglass is flat and the styrofoam is spherical and never the 'twain shall cross without distorting one or the other :) I shudda thought to finish it before I put it all together but also I don't want to get a mess on the rest of it.
 

moocrew

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im doing this now with a nose cone i made from foam like that.
I bought this product called "FOAM FINISH" at my local hobby lobby. its about $4 and you can get an almost plastic like finish with a good sand job. This stuff works great. Im not to sure about weight though...it might be slightly heavier than what you want.

When my nose cone is finished ill post some pics..you really can't tell a difference from my nose cone and a plastic cone. This even w/o any kind of finsh besides regular paint.
 

gerbs4me

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let us know about this foam finish, sounds like the right stuff to use. If it is too heavy, put a bigger motor in it, haha:D
 

moocrew

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Alright here it is....
I tried to get the best shot that i could to show how smooth it is but the black and the clear coat kinda messed that up.
It is incredibly smooth though and the clear coat was pretty much just put on to protect the paint. It pretty much as smooth as any plastic cone you would buy.

The only down side to this foam finish is....that it shrinks, not much but alittle when it dries.
And the only time this becomes a problem is if you are tryin to fill a gash or a deep scar. But it can be compensated for by overfilling the hole just a bit then sanding. It also dries pretty quick.
After you apply you may want to still prime the surface because unless you use an extremely fine sanding paper there tends to be very very very small scratches...like you would see a on CD.

Over all if i rated it from 1-10 i would give it 8.
I got really good results..especially from using that type of rough foam.
And for the price it was defenitely a good option in my opinion.

**Note
The bottom section of the cone wasn't painted with much attention mainly because it sits in the rocket and i saw no point in making it look great.
Thats why there are white "spots".
 

Micromeister

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Moocrew:
Take a pic of the can,bottle or whatever "Foam Finish" comes in. Michael's in my area has never heard of it. Is there a manufactruer's name on the can?

can you give us the length, diameter, and weight of your finished foam nosecone?
Looks like it maybe some good stuff.

Thanks.
 

moocrew

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here the pics of the can....and there is a website and company name on it.


Customer Service:
Signature Crafts, 1-800-865-7238
Beacon Adhesives, Mt. Vernon NY
www.beaconcreates.com

nose cone stats:
weight=3/4 oz.
Height from top to very bottom= 9 in.
diameter at hip= 2 in.
 

rstaff3

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Originally posted by cls
Gerbs, interesting idea to glass it. I didn't want to try glassing it because the fiberglass is flat and the styrofoam is spherical and never the 'twain shall cross without distorting one or the other :) I shudda thought to finish it before I put it all together but also I don't want to get a mess on the rest of it.
The ability of the glass to conform depends on the weave and the direction you lay it. If you check the nature of the weave you can see which way it will conform the best. Lay it in quadrants and it will conform easily. BTW if you search around you will find a better explanation of this process. Try InfoCentral and Google r.m.r. I can't remember the discussion here, but of course try TRF also ;)
 

rstaff3

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Originally posted by rstaff3
The ability of the glass to conform depends on the weave and the direction you lay it. If you check the nature of the weave you can see which way it will conform the best. Lay it in quadrants and it will conform easily. BTW if you search around you will find a better explanation of this process. Try InfoCentral and Google r.m.r. I can't remember the discussion here, but of course try TRF also ;)
Oh, I have done this on BT50, 3", and 6" cones.
 

10fttall

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For coarse styrofoam, like the balls for sale at Michaels, has anyone tried a few coats of Kilz?
 

Micromeister

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I haven't but since Kilz is a latex based primer it should work.
 

10fttall

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This thread is actually from 2004, and I just bumped it.

I don't have an AC Moore, and I've also had trouble finding Foam Finish, but I just found the company's website: http://www.beaconcreates.com/cgfofin.html

Looks like my local options are Michaels, Jo Ann, and Garden Ridge. I wonder how difficult it is to get that stuff smooth on a sphere?
 

rocketking

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With the popularity of foam RC aircraft (that's radio control, for those unfamiliar), there have been several manufacturers of spray foam colored paints. They are usually acrylic paints.

I had read that the new Krylon H2O paints will not destroy foam, but I have not yet tried it myself, so you are on your own.

A trip to a local hobby store & a question like "What do you use to paint a foam airplane?" will get the ball rolling for answers. There was a supply of craft paint that was foam-safe, but I don't have their product or company name. Sorry!
 

m85476585

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I used Krylon H2O primer on foam once to protect it from regular paint (I have a lot of colors of regluar paint so I didn't want to have to buy a lot of H2O paint). It worked fairly well and protected the foam as long as the coats of regular paint were light enough (but I could put the H2O paint on as heavily as I wanted with no problem).
 

10fttall

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I've not been able to find the Foam Finish yet. I have tried a few things as tests. The main problem I have is how coarse the finish is. I think most aircraft parts are probably molded with a tighter exterior finish that would allow simple priming and painting. A styrofoam ball like I want to use is extremely rough. My best result so far has been spackle, but sphere shape makes a nice even surface very difficult, and I don't know how well it would stand up to cracking.
 

m85476585

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I have heard that hardware stores sell a product that you can dip metal parts in, and when it hardens it becomes a plastic coating. I don't know if it would eat foam, but you could try it (or see if the package says anything about solvents).
 

jflis

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Originally posted by m85476585
I have heard that hardware stores sell a product that you can dip metal parts in, and when it hardens it becomes a plastic coating. I don't know if it would eat foam, but you could try it (or see if the package says anything about solvents).
Yep, it's the same (or very similar) to the rubbery material that coats the handles of many tools, like pliers. I don't know if it would react to the foam (I've used it but can't recall the odor or the clean up requirements - which would give an indication of what it may do...). Another concern however is weight. If you were to dip a foam ball into this stuff you would increase the weight of the ball by a factor of 4 or more, I'd bet...
 
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