Question on papering fins...
 

I'm about to start on a new project (finally finishing the Apogee II and Beta that have been staring back at me for months), and I wish to reinforce the fins by laminating them in paper or something similar. In the past, I have followed the following technique:

1) use standard typing paper, and lay down an even coat of spray glue.

2) press the already rounded or airfoiled fins onto the paper. rub firmly to remove air.

3) cover with sheet of wax paper, lay on some books, and let dry overnight

4) cut out fins, and repeat process with the other side.

5) seal edges with thin CA.

Finish rocket as per normal (couple of primer coats, base coat, etc)

Problem is that the paper starts to bubble or lift up (in the middle, not around the edges) after a few months, especially if I fly the bird in high humidity.

Suggestions?

I get self adhesive paper like Avery or the store brand, apply that to the fins using only the stock adhesive, and then seal the edges with CA. I have rockets that were built with this technique for the last 8 years and not a single one has suffered from any lifting or bubbling.

What kinda spray glue are you using? I've had fins papered with 3M for years without lifting or bubbling....

I usually just use regular Titebond II and never had any issues.

3M, same as you...

try using a glue stick or regular white glue. Bonus is glue stick will make the fin stronger than spray adhesive as well as label paper. Using white glue will yield your strongest fin of all four. I typically use 110lb card stock rather than just printer paper. It's a bit more weight but super strong.

White glue is the only kind I use, and my favorite is Aleene's Quick-Dry Tacky Glue (silver-colored bottle). Use a craft stick or some other kind of spreader to squeegee the glue across the paper to get a thin, even coat. You know this next thing but for anyone who doesn't, the glue should be spread onto the paper, rather than onto the fin. Many types of paper can be used, but one that I particularly like is freezer paper. (I use Reynolds brand.) It is butcher paper that has one side coated with a thin layer of plastic. Glue the plain paper side to the fin and you will have a smooth, already sealed outer surface that is ready for primer when you are done. I see no problems with your technique. You are definitely doing it correctly. My only suggestion is to perhaps try another type of adhesive, such as white glue, or as STRMan mentioned, yellow wood glue. Just don't try to adhere paper onto the entire fin with CA; it won't work. As you already know, CA is fine for the edges of the paper, though.

Here's what I do, and it works great... never had a problem and the fins are practically bulletproof.

After you have your fins cut out/popped out/whatever and sanded to your desired airfoil, I grab a couple sheets of regular printer paper and the white glue. Start by laying the fin with the LEADING EDGE toward the center of the paper, with the trailing edge about an inch from the edge of the paper. Trace around it with a pencil. Carefully roll it over the leading edge until it's flat on the paper again, and trace it lightly... doesn't have to be exact, just a general outline of the fin. You should have the first outline of the fin and its mirror image with at least 1/2 inch of paper all the way around both. If you arrange the fins properly you might be able to do all of them with only one sheet of paper, depending on their size and shape...

Apply a THIN layer of white glue to the paper and spread it out THINLY AND EVENLY over the first outline of the fin.... I usually just dribble a few drops of glue and then spread it out in ever larger circles with my fingertip. Once the glue is thin and even, press the fin down inside the first outline. Apply another thin even layer of glue to the top exposed surface of the fin, working the glue out evenly over the whole surface to the edges and over the leading edge a bit. Then simply fold the fin over the leading edge onto its mirror image outline, gluing the exposed surface of the fin down to the paper. Keep the sheet of paper taut (but don't pull too hard-- the paper softens up a bit from the glue!) as you roll the leading edge over onto the rest of the paper to prevent wrinkles.

Now, using a sharpie marker or other "fat" well rounded object, starting from the center of the leading edge out to the fin tip, root edge, and back to the trailing edge, burnish the paper down tight on the fin and squeeze the excess glue out around the edges... I use the sharpie like a "rolling pin" (the kind gradma used to roll out baking dough) which is quite effective at working all the glue out and sealing the paper down TIGHT against the balsa. Use the semispherical end of the sharpie to work the paper down tight against the leading edge, and run it around the outside edge of the fin to seal the paper down tight around the edges and glue it to itself. Flip and repeat on the other side of the fin to remove the excess glue and get the paper down tight and smooth.

Put the fins between wax paper and usually under a couple books overnight. Next morning they should be ready. Cut the excess paper away from them with scissors, down to about 1/4 inch from the fin edges. Then, using a SHARP hobby knife, gently 'shave' off the excess paper down the edge of the balsa on the tip, root, and trailing edges of the fin. It will slice off pretty easily along with the dried excess glue... Once the paper is shaved down to the edge of the wood, I take a sheet of 240 grit sandpaper, lay it flat on the work mat, and gently draw the exposed edges of the fin across the paper at a slight angle, to completely remove any stray 'paper hairs' that might be sticking out after the hobby knife trimming. This also dresses the edges nicely so the root edge is ready for gluing to the model, and the tip edge is smooth and ready for primer/paint.

Glue the fins to the model using regular yellow wood glue and double glue joints-- fins with this treatment glued on with good double glue joints using yellow wood glue will be SO strong, that even landing flat after a power dive from an errant upper stage onto HARD packed bare clay ground, the fin will only get dinged and will rip off the model taking the outer layer of paper tubing with it-- the glue joints and the fin itself is MUCH MUCH stronger than the original materials alone... and there's really no point in getting stronger than that...
White glue is the best adhesive for paper/wood joints anyway-- I still prefer Titebond II yellow glue for fins/tube joints, but for papering fins, white glue is PLENTY strong and easier to work with...

Works for me! Later! OL JR :)

Couple more pics of the process...

What's nice about doing it this way is, it's dirt cheap to do and you already have everything you need close by-- grab a couple sheets of paper from the printer tray and the white glue's probably already on your workbench. Doing the "mirror image" and folding the paper over the leading edge (which takes the most abuse from the slipstream trying to rip the edges of the paper loose in flight and pull it off the fin) eliminates this failure mode entirely, and leaves BOTH sides of the fin completely smooth and ready for priming/painting when you're done... no need to go back and CA around the edges and having to clean up the "CA crusties" afterwards... and no risk of the paper turning loose around the leading edge of the fins either...

Like I said, the printer paper is plenty strong-- with the white glue it practically makes balsa bulletproof... If I could get "stretchable" paper I'd cover nosecones and transitions with it too... LOL:)

Try it you'll like it!

Later! OL JR :)

The few times I tried it, the fins looked great until I hit them with that first primer coat. They didn't look so hot after that.