First, Build a Shed

[Cherrybark]

Ah these pesky forum posts. They can be as bad as emails. My "raw edges" comment did sound kind of snotty and I apologize. I had read your post as non-colored and off I went!

And you are absolutely correct. A big downside of the Oratex systems is lack of paint coats to "soften" the edges along the finishing tapes and joints. Here is a situation where that can be a problem. When applying the top fabric to the wing, I used the straight factory edge of the fabric to make a straight, clean line overlapping onto the underside of the trailing edge. Neat as a pin. However, it is very tough to get a clean, straight line where the fabric overlaps the bottom fabric on the leading edge. You can cut the Oratex fabric exactly to size, but you risk shrinkage and a wavy line while you use heat to bond the glue. So the factory recommends you leave a few inches of "gripping" fabric and do the following:

1. Use masking tape to make a clean glue line on the already attached bottom fabric. Remove the tape before the glue dries!
2. Apply glue to the top fabric so it will more than overlap the masked glue line on the bottom fabric.
3. Attach the fabric, using heat and pressure to bond the glues.
4. The glued surface of the top fabric will not have a good bond to the masked area on the already applied bottom fabric so you can fold the fabric back, make a sharp crease, and cut neatly along the line.
5. Finish by heating and pressing the clean edge of the fabric.

Sounds easy enough and the factory guy doing the YouTube video is an artist. In practice, I had a very hard time getting a straight cut along the creased fabric. The line on my first wing is jagged enough that I masked and applied a couple of coats of glue so it would melt and "caulk" the imperfections in the line. With experience, the second wing went much better. Of course, with so many stages of the project, you are often approaching major jobs as a fresh faced kid.

I'm happy with the Oratex, particularly in light of my complete lack of painting skills and equipment. With care you can do a very nice covering job. But there are downsides to the process.

[aviator79]

For what it's worth, there are certainly steps in Poly Fiber that the manual and the pros make look/sound easy, but the finesse required takes more than a practice kit or two to develop. I guess there's a reason we do this solely for recreation and education. Sometimes more the former than the latter

[efwd]

The triangle edges on my pinked tapes were pretty harmless. Not to say I haven't found some that needed addtl attention..
With regard to the edges not having color. My yellow fabric, once cut, does have a white edge. So, when I cut the holes out for the rudder hinges I had to apply yellow paint on the edges to dress it up a bit. I think that the tapes, being made from the thinner fabric, don't show that same white edge. I bought some sample fabric from the thinner line and when I cut it it doesn't show white.
Eddie

[Cherrybark]

Might send a letter to the editor of the local paper, letting them know I've found another use besides lining the cockatoo's cage. This pattern matches the sides of the fuselage. Should you go this route, be sure to flip the paper when cutting alternate sides.

[Cherrybark]

With the tail feathers and wings complete, I expected covering the fuselage would be a snap. But things didn't work according to plan. The idea was to use the straight factory edge of the fabric to overlap the existing fabric on the fuselage bottom. The technique of masking tape, two coats of glue, then quickly removing the tape, left a neat line of glue. Then I started test fitting the large piece of fabric along the line - using 1" green masking tape to hold things in place. The plan quickly fell apart with the fabric naturally bunched in places and too tight in others because of the nice curves of the fuselage. Being slow to catch on, I doggedly stuck to the plan and spent an entire evening not making any progress.

When things aren't working, walking away from the project usually helps. The next day I used the trick described in applying the top wing fabric. The part of the fuselage fabric that overlapped the bottom fabric had a larger than necessary area of glue. The side fabric was laid with a generous overlap of the bottom and rested neatly along the fuselage. A small iron tacked the fabric in place, followed by a hot air gun and pressure felt along the entire length. Overnight wait for the glue to bond, followed by air gun and hot iron to tighten.

Finally, the excess bottom overlap fabric was peeled back and creased along the clean, straight glue line on the fuselage bottom. Since glue was only on one piece of fabric, there wasn't the strong, glue-to-glue bond. It would take a lot of strength to separate the properly bonded fabric pieces and you will be able to create a straight crease. A sharp, short pair of scissors was run along the crease followed by the iron the secure the edge of the fabric. Finishing tape will complete the job.

[jrevens]

You’ve described pretty accurately how I did it too, Carl. Sorry it was a pain, but your work looks top notch! Keep it up.

[David47]

Great work Carl !. Keep it up. I'm travelling a bit behind you and enjoy your thread.

[bholland]

Carl,
It does look really nice! I have also decided on Oratex and I am always interested in seeing how you guys are doing everything. I tried with the practice kit and I definitely need more help so more practice kits are OTW. It didn't take me long to figure out that the guys in the videos definitely have a talent that I don't. I also wish there were more videos on the application process showing and explaining different scenarios. Everyone one here has definitely been a great help.

Brett

[Cherrybark]

As you can imagine, I'm not crazy about posting this picture. But sharing the mistakes is all part of the forum.

I've described how two glue coated Oratex surfaces have a very strong bond when heat / pressure activated, but you can take advantage of the weaker bond when only one of the surfaces is coated. The technique is to have a sharp glue line on one fabric and a more generous, overlapping glue surface on the second piece. Apply heat and pressure to bond, let cool, then peel back the overlapping fabric to the sharp glue line and trim off the excess. The first time I tried this, overlapping the wing covers, the final creased line was pretty jagged. The second and third time, 2nd wing and 1st fuselage side, gave beautiful lines. This 2nd fuselage side covering gave the mess you see in the photo.

I had a very generous overlap of fabric but it was more securely bonded than expected in some spots and was a bear to peel back. There really was too much overlap to leave in place and most areas didn't have the double glue bond so it had to be peeled back. The photo shows a couple of spots where the glue bond actually peeled the color layer from the fabric.

To be clear, trusting a weak single coat bond between two pieces of Oratex is definitely not a factory suggested technique. In the video linked in an earlier post, the overlapping layer was applied to a type of "masking tape" not to a piece of Oratex. The video doesn't say, but Oratex sells a tape that looks like the material in the video. If you are considering Oratex, it would be smart to call Lars (BetterAircraftFabric.com) the US Rep based in Alaska. Lars is a very down to earth guy and will give straight answers to any questions about techniques.

Oratex glue is activated at 100C and the fabric just begins to shrink at 110C. This conveniently lets you bond the perimeter of the fabric before starting the shrinking process. After some thought, the two situations where I had problems were times that I had completed shrinking, floated a 160C iron over the entire surface, then concentrated heat along the glue lines. In the photo, I was thinking this final step would insure the tubing had heated sufficiently along the entire length. I believe this extra heat "melted" the dried glue and let it bond to both fabric surfaces. When you are applying Oratex to a surface, it's not uncommon to apply a little extra heat release the fabric - to remove a wrinkle for instance. In the two "clean line" situations, I had only used the 110C temp before folding and trimming.

This isn't an earth shattering situation. It's on the bottom of the fuselage after all. Before applying the finishing tapes, I'll use some spare fabric to make a long "patch" strip to cover the area. This is how minor damage to an Oratex covering is repaired so it is certainly suitable for this cosmetic problem.

Finally, yes that is a black fuselage tube showing through the Oratex. To be fair, the top of the fuselage isn't covered, the garage door is open on a bright sunny day, and there is a 4-tube florescent light just above. I haven't rolled the plane out in the sunshine yet so I really don't know how much of the skeleton will show. I won't find it unattractive.

[efwd]

Well Carl, That stinks. Nice thing is, its on the bottom. I had my silver stuff out in the sun and I didn't notice transparency. Not sure if the silver fabric is less transparent or not. The most undesirable thing I have noted is that the yellow 6000 fabric is slightly lighter in color than the thinner 600 fabric that make up the pinked tapes that are applied over it. Eh, not so bad. There is nothing that says I can't use my left over Poly Tone to just paint over the rudder and elevator.