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Foam finishing

Old 04-06-2010, 04:22 PM
  #26  
riverrat
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Default MWWBPC?

Originally Posted by Voyager2lcats View Post
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.
Mr.Voyager21Cats!

Straighten this old head out!!
Is there a MWWBPU? I use MWPU, but have never seen the WB version. MWWBPC works great, & was just wondering if there is a WB version of MWPU And if there is, whats the difference??? Or are they both the same??

THANKS!!!
Jimmy
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Old 04-06-2010, 06:05 PM
  #27  
groundrushesup
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Originally Posted by riverrat View Post
Mr.Voyager21Cats!

Straighten this old head out!!
Is there a MWWBPU? I use MWPU, but have never seen the WB version. MWWBPC works great, & was just wondering if there is a WB version of MWPU And if there is, whats the difference??? Or are they both the same??

THANKS!!!
Jimmy
Polycrylic is just Minwax' brand name for Water-Based Polyurethane.
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Old 04-06-2010, 06:19 PM
  #28  
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Originally Posted by DanWard View Post
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?

... cleans up easily with soap and water....
There's the key to it being safe on foam, taken from the page you provided the link to.....
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Old 04-06-2010, 06:38 PM
  #29  
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Default MWWBPC

Originally Posted by groundrushesup View Post
Polycrylic is just Minwax' brand name for Water-Based Polyurethane.

THANKS!!
Jimmy
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Old 04-06-2010, 07:05 PM
  #30  
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I use Benjamin Moore Stays Clear Acrylic Polyurethane. Yes, it's water based. I always have plenty around for woodworking so I use it on my foamies too.

I apply mine with a Critter Spray Siphon gun:

http://www.crittersprayproducts.com/

Stays Clear sprays beautifully, no bubbles, and dries fast... to fast actually, I have to thin it with 1:4 (water:PU).

My last project was the E-Starter. I glassed the fuse and wingtips with BM Stays Clear and 0.5oz glass. Color is just Acrylic craft paint, then top coated with more BM Stays Clear for durability and gloss.

She came out pretty good:

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Old 04-07-2010, 02:09 AM
  #31  
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Default foam covering

Hi all;
In reading over all the different ways to cover foam, have any of you tried using laminate. Friend of mine gave me a srap roll, and I am tempted to cover the plane with it. Looks like it would go on the same as a monocote type covering.

I think I could then paint over it.
What do you think?
Terry
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Old 04-07-2010, 04:33 AM
  #32  
AirmanAirhead
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Originally Posted by Terry glenn View Post
Hi all;
In reading over all the different ways to cover foam, have any of you tried using laminate. Friend of mine gave me a srap roll, and I am tempted to cover the plane with it. Looks like it would go on the same as a monocote type covering.

I think I could then paint over it.
What do you think?
Terry
I'm not sure what kind of laminate you are speaking of... you're not refering to the stuff used on counter top are you??? If so, I think it's much too heavy per sq. inch, and much too brittle. But then again perhaps you are referring to some other type of laminate.

AA
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Old 04-07-2010, 05:04 AM
  #33  
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Who are you guys/gals buying your silk from?
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Old 04-07-2010, 06:51 AM
  #34  
iflyrc1012
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any fabric shop will carry many types of suitable fabric for finishing your airplane
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Old 04-07-2010, 12:58 PM
  #35  
pd1
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Originally Posted by DEG View Post
Who are you guys/gals buying your silk from?
This where I am buying silk
http://www.dharmatrading.com/html/eng/3374-AA.shtml

This place also sells nice silk, but it seems pre shrunk and doesn't work as well on open areas as the Dharma silk does.

http://www.thaisilks.com/product_inf...22fba3399425a4
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Old 04-07-2010, 02:24 PM
  #36  
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Originally Posted by AirmanAirhead View Post
I'm not sure what kind of laminate you are speaking of... you're not refering to the stuff used on counter top are you??? If so, I think it's much too heavy per sq. inch, and much too brittle. But then again perhaps you are referring to some other type of laminate.

AA

I think he is talking about Doculam or something similar. It's a plastic film that is used to laminate paper documents, etc. I've heard of it before but I understand it's more difficult to paint.
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Old 04-07-2010, 02:59 PM
  #37  
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Originally Posted by iflyrc1012 View Post
any fabric shop will carry many types of suitable fabric for finishing your airplane
Have had no luck at all at the local fabric shops. All they carry are silk scarfs...colorful but not really what we need....lol
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Old 04-07-2010, 03:00 PM
  #38  
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Originally Posted by pd1 View Post
This where I am buying silk
http://www.dharmatrading.com/html/eng/3374-AA.shtml

This place also sells nice silk, but it seems pre shrunk and doesn't work as well on open areas as the Dharma silk does.

http://www.thaisilks.com/product_inf...22fba3399425a4

Thanks PD...that's what I was looking for....
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Old 04-07-2010, 06:35 PM
  #39  
Terry glenn
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Default laminate

Thanks for the quick replys.
No it is not counter top stuff.
Yes it's the light film used to protect papers, etc.
I tried some on some white foam, and it went on like regular monikote, it seemed very strong, and so was wondering abnout using it on a bigger plane.
Also when using a kfm wing, do you leave the step square, or can you wrap the covering over it, so that the air foil, is smooth?, What would the difference be?

Thanks again for all the great info.
Terry
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Old 04-07-2010, 09:30 PM
  #40  
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Exactly.

Originally Posted by groundrushesup View Post
Polycrylic is just Minwax' brand name for Water-Based Polyurethane.
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Old 04-07-2010, 11:00 PM
  #41  
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Originally Posted by Terry glenn View Post
Also when using a kfm wing, do you leave the step square, or can you wrap the covering over it, so that the air foil, is smooth?, What would the difference be?
The step is the key to the KFM design. Without it, it's just another rounded airfoil and you lose some the benefits of the KFM wing.

I have flown KFM wings on a variety of planes and have even flown undercambered vs. KFM on the same plane. I don't have scientific test data, but the KFM has much more gentle stall characteristics at the expense of some drag. I really like it and it's quick to build... no formers, bending curves, etc. Just cut and glue.
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Old 06-09-2010, 03:17 PM
  #42  
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I have used gift wrapping tissue, newspaper, and even heavy brown package paper with either WBPU (Polycrylic) or Mod-Podge (combination of acrylic and white glue, available in the craft aisle at K-mart, Walmart, Micheal's, etc.). I generally use the tissue paper on fuselages and surfaces that I simply want to have a smooth surface that resists hangar rash. For stressed areas like wings, I use the heavier newspaper... it gives the wing more tensile strength. The heavy brown paper I use on the bottoms of belly-landers or for extreme strength on jet wings -- planes that can handle the higher wing loading. For compound surfaces, just make relief cuts to get the paper to lay as smooth as possible... you can always sand away the seams after the glue dries.

First, brush a thin base-coat of "glue" (WBPU or ModPodge) onto the foam and let it dry. Sometimes the glue will dry with a rough surface because of air bubbles that surface from the foam as the glue dries. You can lightly "knock-down" this texture with some 200-grit sandpaper --- not too much sanding though... a little bit of "tooth" is good for the next layer. Next, cut your paper to size and address the problem areas first... joints, curves, angles, and other detailed areas --- go ahead and soak the pieces of paper in the glue then lay it onto the foam as flat as possible -- squeegee excess glue with a credit card then let it dry. Then, address the large flat areas, overlapping the edges a little -- again, squeegee out the excess glue. After the plane is covered and the glue is completely dried, you can sand it smooth with 400-grit sandpaper... be sure to remove wrinkles and seams. Try not to sand through the paper to the foam, but if you do in a few places, don't worry about it. Once sanded, add another thin coat of glue. You can wet-sand the glue once it is dried... the paper won't wrinkle... the paper fibers are now completely impregnated with glue and has become "waterproof". You can continue to add more layers of glue for a smoother finish... I usually do 2-3 top-coats, wet-sanding between each coat.

Check out how smooth I was able to make the wheel-pants on my foamie Goshawk:

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Old 05-05-2012, 12:11 PM
  #43  
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Default tissue and wbpu

I have used tissue and wbpu extensively and think it's great. I use dress pattern tissue that is sold at the local fabric store. On sale it is .99 for a huge amount, in the back where they sell patterns, ask the clerk. The secret is torn diamond shaped bits, the tighter the curve the smaller the piece, not cut edges or large pieces. Both those lead to noticable edges and or wrinkling. Thin coat of wbpu on foam,lay on the piece and work in with wetted brush of wbpu. It goes really fast and smooth and is extremely durable when dry. Paint up any way you wish. Another option is to use colored tissue right from the start such as $tree gift tissue. Nice colors and no need to paint. Avoid pulpy papers.
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Old 06-24-2012, 08:26 PM
  #44  
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So, have you guys tried the shear curtain fabric you get at Hobby Lobby or the fabric shop? I don't know if this stuff is nylon, polyester, polyethylene, or whatever. It works great, though -- easily cut, easily formed, tough as all get out when cured with any sort of glue or WBPU.
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Old 06-24-2012, 08:37 PM
  #45  
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Default Sheer Fabric

I reinforced the pylon on my Polaris with sheer dress lining mache'd on with WBPU, it's about the same if not even lighter. I wouldn't dress the whole airframe with it though. Too heavy for me.
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Old 06-26-2012, 04:12 PM
  #46  
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I used poly-c and super thin glass fibre cloth on my old PZ Spitfire a couple of years ago and it worked a treat as you can see from the picture and video if i can work out how to upload it.
I use this method on all my foamies now especially on the undercarriage as i had to belly land most of them,because of the old field i use to fly at.
It saves your planes from hanger rash quite well and will add a bit of strength,but i doubt theres much out there that will save a real bad crash,unless you don't mind a lot of weight then it still won't be bullet proof.

The lightest glass fibre cloth i could find was over at Hobbyking but you might be able to find the same or lighter else where,any way the HK cloth is 18g/m2 which is there super thin one,the cloth i used on my first go was 24g/m2 and poly-c which i used on the Spitty,still that was still light but i prefer the super thin 18g one plus it's a lot cheaper than the first stuff i used.

[media]http://www.youtube.com/watch?v=Fwp3fX40-qk&list=UUONTiufozL8OoZk4fivhsYw&index=0&feature=p lcp[/media]
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