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Looking for monokote surface prep advice....

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marcm

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I have a new bird that I intend to finish with silver monokote. It will be a first for me other than the intro provided by Jim Flis and his Rose-a-Roc. My main question is about how to prep the surfaces that will receive the monokote. There will be both cardboard body tube and balsa fins.

1) Am I better off giving a coat of primer or laying on the bare material?

2) What about spiral and/or balsa grain filling? My tube isn't too bad but I am not sure if the monokote will hide the imperfections or make them stand out.

Any tips, advice, do's, don'ts or other words of wisdom are appreciated!

Marc
 

mjennings

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I've only monokoted a rocket once and it was probably too small of a rocket. I got 3 flights then a crash and burn, not sure if the monokote played in the fire starting. I don't know if you need to primer, it goes on bare wood all the time. as long as you are pretty dust free and the spirals are reasonably small you should be good. You can always do a test on a scrap piece of tube.
 

JoeG

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I wrote an article for Info Central a few years ago and it is still out there.

I have been experimenting with different covering materials lately and have found that hanger nine's Ultracote is a little easier to work with for rocket applications than Top Flite Monokote. It has a lower "beginning to shrink" heat range which is good when covering cardboard tubes without crushing them and it seems to be a bit more forgiving if you do get a wrinkle or two just turn up the heat a slight amount and it shrinks out.

As far as surface prep goes i have done it both ways. Any surface imperfections will be magnified when covered with anything shiny. I have covered body tubes with no surface prep at all and fins with only sanding and had excellent results.

My most recent project was primed and I was just getting ready to start filling the spirals when I decided to try to Ultracote the whole thing rather than paint. I sanded the primer to make everything smooth. Any little speck under the covering is magnified greatly once it's covered up so take a little extra time and get that little glob of glue or piece of dirt off the airframe.

How does it look? I think it turned out pretty good. You can be the judge.
Here are some photos.
http://s148.photobucket.com/albums/s20/joeG_album/upscale cherokee/

The covering seemed to stick better on the promer but you have to be careful not to trap air under it. Always overlap from front to back (Start covering at the back and work your way to the front so the air[ when you are flying] doesn't get under the seams.)

Joe
 
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powderburner

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Any surface imperfections will be magnified when covered with anything shiny.
This is true, very very true. ANYTHING that is under the monocote (or any other plastic film covering material) will show. Clean it, wipe it, vacuum it, and then clean the surface some more.

If you are applying this stuff "model airplane" style (ironed onto the edges with the center left free to stretch) it won't be quite as bad. Remember that while this stuff does stick to balsa, it sticks to itself much better. If you start at the trailing edge on one side, wrap around to the other side, wrap around the leading edge and back onto the first side, then finally stretch the material back to the trailing edge (over the top of the strip you started with), you will usually get the best adhesion. Yes you will iron both sides of the TE, but you will still need to iron a strip of the LE also.

Eyelashes show underneath this film. Specs of dirt, balsa dust, etc, stick out like a sore thumb.

If you are applying this stuff to the flat side of a fin (and ironing it) I am afraid you will see the grain of any unfinished balsa.

If all you want is a shiny chrome/metallic finish, there is a thicker "trim" monocote material available (in chrome) in sheets of 6 x 36 inches. This is peel-n-stick, with no ironing, and might be an easier finish for you if your fins have straight edges. You would wrap the same way; TE, around to the TE on the other side, around the LE, back to the TE, giving you a smoothly covered LE to your fin.
 
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