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Foam finishing

Old 01-29-2010, 03:10 AM
  #1  
rleed
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Default Foam finishing

I'm finishing a GWS Zero. I've got it all smoothed up and ready for paint. I have also read through the threads on using silk and wbpu. Has anyone ever tried to use tissue with the wbpu. Im going to test some on a chunk of scrap tomorrow. Also would just a couple coats of wbpu give the foam some added durability against hangar rash? The raw foam is easily marked even if you brush it up against something. Should I brush on the wbpu or airbrush it? Thanks in advance, RLeed
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Old 01-29-2010, 03:29 AM
  #2  
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well, foam finishing is one of my very few strong points. Tissue will tear when wet. U need a weave. The weave is what gives it intergrity. Personally I use .5 oz fiberglass and minwax poly. I start with one coat make sure you dont get any bubbles or seperation. I use an artist brush. overlap the leading / trailing edges by about 1/4 inch. the "wrapping" technique will yield maximum strengh.. Once dryed I use a medium sandpaper...make sure you get it smooth where it overlapped on the leading / trailing edges to give a matte surface for the glass to ahdere to, (do the bottom first, then the top)then reapply poly to glass. On the second coat, I sand all the way down to a 2000 grit, that i get from the auto parts store. Makes a super sexy strong amazing finish. And very light. for your application, weight may be more of a factor... but the glass is super thin and light. try it out. its fun to do too.
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Old 01-29-2010, 03:42 AM
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Thanks, I have a bunch of .5 oz glass. I'll give it a try on my scrap.
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Old 01-29-2010, 04:17 AM
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Not a problem man. Happy to talk if someone will listen.

Last edited by Major-Gforce; 01-30-2010 at 12:47 AM.
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Old 01-29-2010, 06:04 AM
  #5  
Matt Halton
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I use tissue and WBPU on foam all the time,and very successfully.
With the GWS zero, it might be more prudent to use this method over glass (for the weight factor) Nothing wrong with a glass finish, but in this application, you might find tissue better,I have used this system on many foam models,it's pretty tough and you get a great finish too.

Matt
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Old 01-29-2010, 03:55 PM
  #6  
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Thanks, I'm going to do some trials on some scrap. I'll try just wbpu, tissue and the glass. Weight is a big factor. I'll try and post up the results. Thanks again.
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Old 01-29-2010, 05:02 PM
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I prefer silk or glass cloth and wbpu, but I did a GWS Corsair with silkspan ( paper product a little stronger than tissue).

The silkspan worked well, the only problem was that it didn't want to do compound curves.
I layed the silkspan down and using a foam brush I brushed it from the center outward with wbpu.

Worked well, even for me.

Paul
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Old 01-29-2010, 05:21 PM
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Originally Posted by pd1 View Post
I prefer silk or glass cloth and wbpu, but I did a GWS Corsair with silkspan ( paper product a little stronger than tissue).

The silkspan worked well, the only problem was that it didn't want to do compound curves.
I layed the silkspan down and using a foam brush I brushed it from the center outward with wbpu.

Worked well, even for me.

Paul
Ah the Super Corsair. Did you massively overpower that plane like the real thing?
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Old 01-29-2010, 05:42 PM
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Originally Posted by groundrushesup View Post
Ah the Super Corsair. Did you massively overpower that plane like the real thing?

Of course.
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Old 01-29-2010, 10:13 PM
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thats the beauty of .5 oz cloth...It wraps around corners and edges nicely, and when a corner is not 100% perfect, u just sand it smooth, apply a touch of minwax and bada bing bada boom, perfectly smooth contoured corner.
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Old 01-30-2010, 12:32 AM
  #11  
rleed
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I tested 3 different methods. The bare foam with just wbpu will sand smooth and look good but is still not very durable. The wpbu and tissue works very well, leaves a very smooth surface and adds a "skin" that increases durability. It will work fantastic on smooth surfaces such as wings, and tail feathers. Curves require a little more care and you may have to settle for a small wrikle here or there. The .5 oz glass lays down really nice and will make a really slick finish with additional coats of poly and wet sanding and perhaps a little filler primer and it is tough as nails and goes around curves beautifully. I think what I am considering is tissue on the wings and horizontal stabilizer and glass on the fuse and wing leading edges. Thanks to all, RLeed.
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Old 01-30-2010, 12:46 AM
  #12  
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Glad to help man. Enjoy!
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Old 03-03-2010, 03:51 AM
  #13  
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Default ok I'm an idiot but what i s wpbu????

hey guys im new to foamies and building a gsw 262 and wondering the best way to make it look like metal instead of foam looking for ways to seal,prime and paint it any suggestions?? I have built a few in my life but just getting into this electric mess
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Old 03-03-2010, 04:01 AM
  #14  
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Originally Posted by Major-Gforce View Post
well, foam finishing is one of my very few strong points. Tissue will tear when wet. U need a weave. The weave is what gives it intergrity. Personally I use .5 oz fiberglass and minwax poly. I start with one coat make sure you dont get any bubbles or seperation. I use an artist brush. overlap the leading / trailing edges by about 1/4 inch. the "wrapping" technique will yield maximum strengh.. Once dryed I use a medium sandpaper...make sure you get it smooth where it overlapped on the leading / trailing edges to give a matte surface for the glass to ahdere to, (do the bottom first, then the top)then reapply poly to glass. On the second coat, I sand all the way down to a 2000 grit, that i get from the auto parts store. Makes a super sexy strong amazing finish. And very light. for your application, weight may be more of a factor... but the glass is super thin and light. try it out. its fun to do too.
Hey Major,

So here's a clarification. It sounds like you are doing the following steps.

1.. a first coat of WBPU, no glass, then sanded with med. paper.

2. second coat of WPBU with glass, correct? Then sanded with 2000 wet or dry paper.

My question is that makes just two coats, (base coat) and one coat with the glass, does that fill the glass enough for sanding? I know we don't want to get too heavy with this, just wanted to get it clear.

I really enjoy making foamies, but get frustrated with doing a good paint job on bare foam only to have it get marked up, from heavy wind

thanks AA
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Old 03-03-2010, 04:15 AM
  #15  
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Originally Posted by pd1 View Post
I prefer silk or glass cloth and wbpu, but I did a GWS Corsair with silkspan ( paper product a little stronger than tissue).

The silkspan worked well, the only problem was that it didn't want to do compound curves.
I layed the silkspan down and using a foam brush I brushed it from the center outward with wbpu.

Worked well, even for me.

Paul
Nice aircraft Paul...
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Old 03-03-2010, 12:07 PM
  #16  
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Originally Posted by lilwildrabbit View Post
hey guys im new to foamies and building a gsw 262 and wondering the best way to make it look like metal instead of foam looking for ways to seal,prime and paint it any suggestions?? I have built a few in my life but just getting into this electric mess
Here's a thread I did on finishing foam planes.
Skip to the end and see if that is the finish you are looking for.

http://www.wattflyer.com/forums/showthread.php?t=22327

If you are looking for more of a metal look, you'll have to try searching for aluminum tape.
There might be a thread on it here, if not rcgroups will have one.

Last edited by pd1; 03-03-2010 at 04:51 PM.
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Old 03-03-2010, 12:07 PM
  #17  
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Originally Posted by Airhead View Post
Nice aircraft Paul...
Thanks Bruce.

Paul
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Old 03-03-2010, 01:11 PM
  #18  
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Originally Posted by pd1 View Post
Here's a thread I did on finishing foam planes.
Skip to the end and see if that is the finish you are looking for.

If you are looking for more of a metal look, you'll have to try searching for aluminum tape.
There might be a thread on it here, if not rcgroups will have one.

Where's the thread? No Link?

Thanks,

AA
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Old 03-03-2010, 04:52 PM
  #19  
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Originally Posted by AirmanAirhead View Post
Where's the thread? No Link?

Thanks,

AA
Sorry about that, I think I have oldtimers.
Link has been added to last post.

Paul
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Old 03-04-2010, 01:11 PM
  #20  
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just my $0.02 here...

If you can find the brown paper towels that comes in a roll, it makes a great covering material as well. It is the stuff used in most restroom dispensers in public and business offices. Its much like Kraft paper, but much thinner/lighter and still has the long omni-directional fibers as the heavier stuff. You can use either thinned Titebond or WBPU to apply it. The resulting finish is very tough and STIFF.

After doing some testing I have found the following:

Finished weight: ~0.42 oz/sqft when covering two sides of foam or ~.0.21 oz/sqft for single sided skin. As a comparison, 0.75 oz fiberglass applied with WBPU is about 0.55 oz/sqft for both sides skinned.

Sandability: Easier than light glass and Kraft paper, but harder than tissue paper.

User Friendlyness: Very easy to handle after being pre-wetted for application. You dont have to be very gingerly with it like tissue paper.

Cost: Free - if you dont buy a roll

Last edited by wingnutt; 03-04-2010 at 01:14 PM. Reason: txt
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Old 03-04-2010, 11:41 PM
  #21  
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Thumbs up Silk and polyurethane

I am going to echo Paul (pd1) on silk and water based polyurethane (WBPU). Silk goes on easy with water and a brush for initial adhesion. Then gradually brush on your polyurethane. I have had my Minwax Polycrylic WBPU so long that it is a bit thicker than when purchased. Easy fix: add some water to it in a shallow foam cup, mix it, and brush it on. Nothing compares for strength and light weight.
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Old 03-05-2010, 02:46 PM
  #22  
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when using silk, tissue, brown paper or anything else that expands when wet, warping during drying is always an issue. If one were to use epoxy (which doesn't shrink when curing), wouldnt that keep things straight? once the fibers expand from soaking up the epoxy, they should stay that way, right?

to keep the weight to a minimum, you can wrap your work piece with plastic wrap, grocery bag, visqueen or anything polyethylene then squeege the dickens out of it with a credit card. its amazing how much glue you can extract this way.

the only thing is, for best effect you need to leave the plastic on until the part is done curing. this cannot be done with water based adhesives since it needs exposure to air to evaporate. epoxy would be the way to go here i think.

Last edited by wingnutt; 03-05-2010 at 02:50 PM. Reason: txt
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Old 03-06-2010, 01:44 AM
  #23  
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wingnutt, I have never had foam warp while drying under silk and polyurethane. I have a P-40 and a P-47 that both have silk and polyurethane on them and they fly wonderfully.
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Old 04-06-2010, 01:01 PM
  #24  
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Question WBPU - Is it still available?

I'm new and building a Multiplex foam plane. I've been reading in this forum about finishing / painting foam and see all the references to WBPU. I was not going to tissue or glass the plane. I was just planning to use WBPU as a primer coat to get things sealed and sanded smooth. Then some acrylic water based color. Followed by a top coat of WBPU. I enjoy playing with my spray gun. I beleive I could keep things light and end up with something a bit more unique that just using the Acromaster decals.

A couple of years ago I used Cabott's WBPU on some doors as part of a kitchen remodel project so I know it used to be available. Back then I applied it with a spray gun and it bubbled like crazy. I ended up spraying it on and then brushing out the bubbles. The point being I have experience and was very confident I was going to be able to purchase it.

The Cabott I used in the past was purchased at Lowes, they still carry Cabott but not the WBPU, only oil based. The "guru" at Lowes said it was discontinued.

Both Lowes and Home Depot carry Minwax product but instead of something called WBPU I find they now sell something called "Minwax® Polycrylic® Protective Finish". Everything with Urethane in the name was oil based.

So is anyone else having troubles purchasing WBPU? Or is the Minwax® Polycrylic® Protective Finish the same thing and I'm just confused?
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Old 04-06-2010, 03:00 PM
  #25  
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Dan, Minwax Polycrylic is a water-based polyurethane. The container is/was blue overall. I think you have the correct can. The contents looks like condensed milk.
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