Another Finish Variation

Here is a finishing technique that I’ve not seen on this forum.

There is nothing I love more than to see a well executed dope and silk/silkspan finish. And, there are many on this forum that are experts in accomplishing it. However, it is not for me. Neither I nor the head of my household can stand the long-lasting, penetrating smell of dope – plus, I’m too lazy to spend the countless hours involved, even if I had the skill.

Since I’m a sport flier, I have often used some of the other techniques to get a finish that will not completely shame me, not weigh a ton, and yet is relative easy and quick: rattle can paint, Monokote, polyacrylic, etc.

Monokote is a good finish – it is light, shiny, very fuel proof, quick to apply, no odor, requires simple tools and relatively inexpensive. However, it does wrinkle in varying temperature and humidity conditions – some call it “Wrinklekote” – and can bubble when being applied, especially on solid surfaces. It also can be difficult when using Monokote over monokote on open surfaces. It does take a technique to apply well (something I’m still learning since it came on the market many years ago!)

Here is a slight variation that I’ve used that helps with Monokote (or any of the plastic films), on both solid and open surfaces:

Cover everything with Koverall – yes, it is heavier than silk or silkspan but weighs only 1.5 oz per square yard. I put it on with Balsarite around the edges. Like many of you, I’ve found if I paint Koverall, I end up with a very large weight gain or a very poor finish (or, in my case, both!). Instead, I put two coats of nitrate on the Koverall then cover with Monokote – the nitrate is said to stabilize the Koverall. The Monokote goes on extremely well, without bubbles, even on the solid surfaces. (I think the weave gives someplace for some of the gases to go from the Monokote glue.) Yes, you may/will see some of the weave but from a couple of feet away it looks very good.

The real advantage, however, is the long-term effects. On several large RC planes covered this way, I have had no bubbles in several seasons. Also, because of the fabric substrate, fancy patterns are much easier to do since you can have cutouts in the Monokote and it still goes down easily.

I’ve tried using silk on open surfaces instead of the Koverall and it works equally well. It is also cheaper and lighter than Koverall but takes a little more work and skill to apply. I’ve not tried silk and Monokote on solid surfaces yet.

Hope this is of interest.

Monocoat over silkspan on wings works pretty well. Watershrink the silkspan with a little bit of titebond in the water. The monocoat will stick to the silkspan very well and you get a very rigid structure. I used to do slow rat wings that way.

Jim

Did you have to put the Monokote on the silkspan at very low heat? Otherwise, since the silkspan is nonporious, I would think there would be a tendency for bubbles. I have heard that using dilute titebond is also a great primer for bare wood.

>since the silkspan is nonporious,

Silkspan Nonporious ????? You can blow air through it, guess I don't understand.

never mind
disregard
forgetaboutit

This technique may work well on large RC models, where there is an abundance of power. Probably too heavy for most CL applications, however, except, as you say, for the sport flyer.

There may be some durability plusses here, of course. Currell

When finishing my Legacy, the one in the product review section of this forum, I used monokote over slightly doped silkspan for the flying surfaces. BTW, There's more than enough porosity, even after two coats of thinned dope.

I didn't have to reduce heat, but there is a learning curve when it comes to application. It's all outlined in the Legacy post, if you want to read about it.

The plane is now almost a year old, and even though it's been dorked in, inverted, at the Regionals, and under going repairs, the covering on all the flying surfaces are not showing any signs of bagging or bubbling that's often common with plastic coverings.

The finish looks soo good that the next plane will also have a monokoted fuselage.

An added advantage is that the finish comes out at about the same weight for a similarly finnished all silkspan and dope finish. But, it seems to be cosiderably stronger than the traditional finish. In addition, by using transparent plastic over the silkspan, you wind up with the classic dyed dope look in your finish. As noted, very complicated trim schemes can be more easily accomplished over a silkspan substrate.

I believe this is a good alternative finishing technique, esp. for those who cannot easily completely paint their planes.

I too, have used mono over Sigs Koverall, with about the same results. But, it was heavier than mono over silkspan. It was extremely tough though, and for the builder with a large weight budget, and a propensity to have less than perfect contacts with the ground, is an excellent way to help survive this ground contact.