Surface prep
 

Building a top flite P51 and have the horizontal and fin nearly completed, cant finish the fin until it is attached, but is there anything I can seal the balsa with before covering it? Something that can harden the wood a bit, and help protect it until I have the plane assembled and covered with Monokote?

The horizontal looks good, so does the fin. Been quite a while since I built a plane, but its coming back. used some balsa filler to smooth out where the ribs were a bit low. Looking good.

Oh, can Monokote be applied to the plastic cowl and radiator scoop?

RE: Surface prep
 

I just store completed pieces out of the way. dont cover plastic with mono.. heat required will melt it. if its gas.. cant you just paint the cowl?

RE: Surface prep
 

acdii,

I would use clear nitrate dope to seal the balsa.

You have to consider that I am a "dope man".

Apply it with a brush. Donot spray it.

I am not really qualified to advise you concerning Monokote on plastic.
If no one shows up on this point of view I would think that a test can be made.
It would depend on the type of glue used by Monokote on their film.
I would use some 180 or 220 grit before application.

Zor
.
</p>

RE: Surface prep
 

I'm modeling mine after Macon Belle which is polished aluminum. I will be using chrome monokote which will be hard to match with paint. I will get some red dope since the tail is going to be red monokote. One coat or two for good coverage? I dont want to add too much in weight so fewer the better.

RE: Surface prep
 

Use 30 minute epoxy thinned 50/50 with 91% alcohol. You only need a couple of grams. The small amount of weight versus the resistance to hangar rash is well worth it. At most you only need about 10 grams. A gram is about the weight of a dollar bill!

RE: Surface prep
 

Is it the 1/4 or 1/7th scale TF?  I painted my 1/7th and it came in at 10.5 lbs.  I have a 1.20 4s on it and it has plenty of power.   It is too hard to match film coating with paint so I painted the entire model.

RE: Surface prep
 

Was it a two part catalyzed paint or solvent based? It makes a lot of difference.

RE: Surface prep
 

Hi!
Do not paint anything on the balsa surface prior to covering with plastic film!!!!!!
The plastic film will not adhere as well if you do!
And do not use Chrome Monokote! Oracover is much better!

If you want an aluminium look to your cowl , use alu duct tape!

RE: Surface prep
 

Jaka
That's some nice work.
acdii
I use hair spray between 220 grit and 320 grit sanding. Makes the fibers stand up for better sand job, adds a little glue to the wood to make the covering stick better, don't knock it until you try it.

RE: Surface prep
 

As easy as it is to use glass cloth and epoxy, I would do that. Or you could use a water base poly floor finish. Down side is you have to paint. Upside is no worries about matching colors. Most paints are fairly easy to apply. Top coat with a urethane base clear for fuel proofing. Take it to a local body shop for that if you don't have the skills or equipment. Tell them not to much, ( lite weight ) only enough to seal and a tiny bit extra for sanding and buffing if needed. Many threads on painting, so do a search.

Ken

RE: Surface prep
 

Like Jaka I don't like to use anything on the wood. There are several things you can use to make the covering adhere better. Lacquer hair spray is one, Balsarite is another. The problems come when you want to recover. I'm going through this now on a plane someone used something on. What a pain in the hinderpoo.
Usually I would say the same thing as Jaka about the covering you use but to date the only Ultra I have ever had a problem with is the aluminum and chrome. That was a first for me. I went with Mono and it shrunk and stuck a lot better?????? That went against everything I know about the two coverings but I this case the Mono just worked??[X(]

RE: Surface prep
 

So 10 grams would be the same as a ten-dollar bill?? :D:D:D Sorry-couldn't help myself;)

RE: Surface prep
 

http://www.rcuniverse.com/forum/js/f...eeth_smile.gifhttp://www.rcuniverse.com/forum/js/f...sn/biggrin.gifhttp://www.rcuniverse.com/forum/js/f...wink_smile.gif

and a $100.00 bill weigh 6.25 oz which is 1/4 lb.

Hee! Hee! ................ funny.

Zor

RE: Surface prep
 

You got it! You got it! :)

RE: Surface prep
 

<span>Looks like the </span><span style="font-family: Verdana, Arial; font-size: 13px; background-color: rgb(251, 252, 255); ">Oracover </span><span> is Ultracote here.   Price is close to Monokote so I will give it a try. I have a Guillows B17 that I can test it on. </span>

RE: Surface prep
 

Hmm I came across something that said you can activate the adhesive in MonoKote using Windex. I wonder it that would work to attach it to plastic.

RE: Surface prep
 

Just take a small piece and try it out.

Zor

RE: Surface prep
 

Well after much experimenting, Monokote does not stick to plastic very well, with both the solvent or heat. It will stick, but comes off too easy for me to spend the time to cover it with the film. 

I compared stick rate with applying it to the stab of my B17 and to the cowl, left a bit of film unglued on both and after cooling, gave them both a tug test with gravity, and it came right off the cowl but stuck good to the wood. When it came off the wood, part of the wood stuck to it.

Looks like I will be going with a modified scheme by using a red nose like Princess Elizabeth has in blue, so that I can stay with the red tail and yellow stripes with the highly polished skin.  When I look at the placement of the paint lines on the cowl, and compare them to the model, then the line falls right behind the plastic cowl, so it will be painted.  The only part I will have problems with then is the radiator scoop under the wing since it is also plastic.

BTW the cowl plastic does take a good amount of heat without softening or deforming.

RE: Surface prep
 

I prep plastic coverings with acetone thinned nitrate dope. It sticks to everything, and everything sticks to it, and it does a dandy job of encapsulating microscopic balsa dust from prior sanding operations.

The only thing that sticks to exposed dust is ummm...more dust.

The nitrate dope is also an effective wood hardener. I use it a lot during ARF repairs for other people when the original plane's wood selection was dubious.

RE: Surface prep
 

cutaway.

I just have to back up your posting because genuine dope has wondeful characteristics and usage.

I mean by "genuine dope" the undiluted dope obtained from the same sources as the full size airplane rebuilders are using; Dope like Randolh or Brodak.

My models all had carved wood cowlings before I built my Skybolt which has a plastic cowling and wheel pants.
After removing the G90 engine which was mounted sideways and patching the big holeI had to paint that cowling and I simply doped it. That was over a year ago and it is just fine.

To my knowledge dope is basically an acetate or cellulose like a celluloid.
As you imply, dope willt grab to anythng and anything will grab to dope.
Women use it to color their finger and toe nails. A different brand name and much more expensive but basically the same.

Diluted nitrate dope penetrates deeply into the wood, seals it and reinforce it.

I even enjoy the smell of aircraft dope. To me it is a perfume but always use it with good forced ventilation.

Thanks for your posting. I would hope that many modelers take notice.

Regards from Zor.