First, Build a Shed

[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.