I just bought a used low wing aircraft covered in Ultracote. covering the engine area is what I'm interested in advice about. My trainer was the same way as well as other areas on this low wing aircraft.

The fuse sides extend beyond the firewall to about 1" from the prop. The inside of the engine bay is doped or something and painted black. The covering is applied to the sides of the fuse and along the sides of this engine bay.

My question is: Where there is an exposed edge on the covering, where the covering meets the painted surface, the covering tends to lift in this area. I've tried CA but it doesn't really seem to work. Epoxy under *cote makes an ugly bubble for some reason.

What's the secret here? Is there some sort of rubber/plastic trim that I can use and glue over the exposed painted/coating edge?

Spiral_72, there are 2 things that you can do.

First you can mix a small amount of epoxy with rubbing alcohol (to thin it out) and brush it over the area or you can use clear nail polish. Both will help seal the covered area and reduce the risk of torn covering.

Hope this helps.

-Joe

Hi!
Easiest thing is to sand the black paint away and cover the fuselage frame with Oracover (Ultracote in the US).
No plastic film will stick to a painted surface. However...Oracover stick very well (extreamly good) to a micro balloon covered and sanded surface, especially if the Micro balloons have been mixed with polyester resin (Not epoxy).

Spiral 72, what has worked well for me is to mix 15 min epoxy, thin with rubbing alcohol, I make mine fairly thin then apply with a small brush, also I use tape to mask off around the covering making a neat line, this has work well for me. Never a problem with covering.

Just a comment. If a surface is painted with DOPE, covering film will stick to it. The heat activates the dope and makes it act like an adhesive. I've done this many times and it really works.

clear finger nail polish. I've read before you can use it to keep decals from lifting. I don't know whay I didn't think of that.

I've mixed epoxy and microbaloons together for a filler. It works well, but for sealing the balsa!? I'll have to try it. Epoxy is fairly tough for me to sand. Maybe it's easier if you thin it like you mentioned. I'll try it tonight.

What's polyester resin? Forgive my ignorance.

The Ultra cote does seem to stick to the dope well. The engine compartment is not sanded an is therfore very porous (SP?). (I didn't build the plane) I could use the epoxy/resin filler to seal it though. I guess that'd kinda replace the doped surface though.


Thanks all! I think I'm gonna try either thinning epoxy/microballons or the resin idea, if I can find the resin. I think it'll work nicely if you say the coating will stick to it.

I gotta 'nother question too, but I'll put that in another post.

A couple of things need to be said here.

If you're going to thin epoxy, use acetone. It's for thinning epoxy. If you must use alcohol use denatured. It's 100% alcohol and won't contain water unless you leave it open overnight.

Ultracote does stick to painted surfaces. Sometimes it helps to sand the painted surface. If the painted surface has been exposed to fuel residue, very little will stick to it. Unless you clean it very thoroughly. Acetone works good for this.

Polyester resin is what fiberglass used to be laid up with exclusively. It is a resin that is catalyzed with drops of chemical instead of the almost equal parts being mixed. It creates a very strong fiberglass that is appreciably more brittle than fiberglass laid up in epoxy. Boats used to be polyester resin fiberglass. They'd actually wear out as the stuff shattered internally. Boats are now mostly epoxy and still wear out but not nearly as fast.

Polyester resin is much cheaper than epoxy to build things with. It creates things that are way more apt to eggshell when crashed. It's less flexible and more brittle. A buddy of mine went through a bunch of fiberglass airplane models last year. Every one of them was not worth trying to repair after ANY kind of damage. They eggshelled all over. One big bomber basically did an flop landing and darned if almost every fiberglass part eggshelled. We walked up to it expecting to see the gear messed up and maybe a spar or such busted and found something that looked like it'd been hit by a deathray or sonic killer pressure wave. No doubt it was all polyester resin glassed.

And thinning epoxy with rubbing alcohol is like pouring some water into the epoxy. Water molecules trapped in epoxy weaken the epoxy structure. And weaken it's adhesion to glass cloth and everything else. The epoxy also winds up curing with pores in it where the water was trapped. When it's trapped inside the epoxy it weakens the structure. When it's near the surface when the epoxy kicks it creates pores. The pores often keep thin epoxy from fuelproofing or waterproofing.

If you're going to thin epoxy, use acetone. It was made to do the job. It's in home improvement stores, hardware stores and paint stores. And it's cheap.

It's cheap and also great to have around when you get CA on Ultracote/Monokote. It wipes it off. And it preps painted surfaces that are going to be decaled or filmed.

to much good advice for me to add to except degrease as good as possible first but then you knew that

I got much more info than I expected. I'm making a house parts run tonight..... I didn't get to work on the plane the other night and try to alcohol/epoxy thing because had to fix the pipes on my house.... Brother.

Anyways I guess it's a good thing I didn't. Acetone is on the list of stuff to buy tonight at Lowe's... Thanks!

I did some repair and covering last night though. Man that Ultracote seems to work so much better than Monocote (for me)....... Very cool.

Personally, I've not had much luck with epoxy and covering.

Epoxy often developes a waxy surface that covering won't stick to, and epoxy doesn't stick well to plastic. So having epoxy either under or over the covering isn't a good idea.

You said this plane is used - That's the problem. Once the engine compartment has seen fuel oil it will be tough to clean it all off.

If it were me, I'd clean it good with alcohol or acetone, and I'd be prepared to repaint if necessary (Acetone might eat the paint). Once the surface is CLEAN and fuelproof, apply the covering, then wick some thin CA along the edges of the covering.

All these ideas are great but a problem Im seeing is that CA has already been used on the area. Once you use CA or most other glues, nothing else will stick to it, it has sealed the wood and CA is the hardest to get off.
If posible, replace the wood in that area and start over. I have very good results applying thinned epoxy to the covering edge to seal it to the balsa and then paint the firewall. Try to use CA as a last resort for covering repaires.

I noticed that nobody has mentioned the use of K2R to draw out as much of the grease and oil as possible before going forward. It is a sprayed on item that goes on wet and dries while pulling out the oils. It is in the grocery (at least it used to be). I have a can that I bought several years ago. I've only needed it one time since I bought it. It works great. Anyhow, try it then do all the great things the above modlers have suggested. They are all great ideas.

I have not mentioned K2R because the problem does not seem to be oil-soaked wood, but rather a painted surface which has oil on it

Oil is oil. If you want to get rid of it, that is what K2R does.
You could always wash it with water and Dawn Dishwashing Liquid.
It removes oils.
I wash my clothes with Dawn after I have worked in poison Ivy. In fact, I wash my arms and hands with it to get rid of the oil.
So much for that, I'm done. Thanks for listening.

K2R is best used for removing oil from porous surfaces, like wood, or carpet where the oil gets deep down in there and needs to be wicked out.

True it will work on a non-porous surface, but you need to spray it on, let it dry and wipe it off. It's much quicker to just use a good solvent like alcohol or acetone.