Paper on Fins?

[zeke1312]

I've seen posts that reference applying paper to fins for strength and a smooth finish. My question is exactly how to do this? What kind of paper and glue? Quanity of glue to use? Trim balsa after paper is applied? How well does the balsa and paper sand?

Thanks

[stefanj]

You have a lot of choices.

I've used CA and silkspan, and yellow glue (carpenter's glue) and silkspan.

I've heard of others using white glue and good quality bond paper.

The trick is to apply the stuff after all sanding is done. Use the fin template as a pattern to cut out a "skin."

If the fin shape is simple, you can make a double skin that wraps around the leading (or trailing) edge.

Another possibility is to make the skin slightly undersized. This will leave the fin's edges exposed. You can cover them with seperate rectangular wraps.

Apply a thin coat of glue, apply the skin, and place between two pieces of waxed paper. Weight down with books and leave it be for a few days.

Follow up with some coats of slightly thinned glue.

Raw paper doesn't sand well, but if it has been "stiffened" with glue or filler you can work with it.

[sandman]

I've seen posts that reference applying paper to fins for strength and a smooth finish. My question is exactly how to do this? What kind of paper and glue? Quanity of glue to use? Trim balsa after paper is applied? How well does the balsa and paper sand?

Thanks

I've done this on a few models with some really good results.

It works best on scale fins. Usually scale fins have a diamond ore similar cross section which is relatively hard to sand accurately.

I use 110# cardstock and use straight out of the bottle white Elmer's glue but spread thin and evenly. I use a piece of plastic like a cradit card and squeegee it even on the surface.

I usually draw the fin in CAD and print the cardstock out first then I cut it to fit.

The balsa is cut "slightly" oversised then sanded to fit the cardstock when ther glue is dry.

The LJ II fins are "wedge" shapped and are made from R/C airplane trailing edge stock so all that was left was to add the leading edge. Trhe pic should show how they came out.

BTW, this was my prototype.

The great part about using this method is the simplicity. No more sanding after trimming the balsa to fit the paper. Just paint.

I will admit it doesn't work on every design.

It will work on teardrop shaped fins but it's harder to do.

[CPMcGraw]

I've seen posts that reference applying paper to fins for strength and a smooth finish. My question is exactly how to do this? What kind of paper and glue? Quanity of glue to use? Trim balsa after paper is applied? How well does the balsa and paper sand?

Thanks

Zeke,

Some of the posts were using the paper-over-balsa technique more for the simplification in finishing it offers than for the reinforcement (although that is an added benefit). One method that I've started using, and which others have been using for a while now, is to pick up a package of full-sheet self-adhesive printer label stock from Staples, Office Max, Office Depot, etc. Use the house brand, as it does just as good a job and is less expensive. If you print the fin pattern onto the sheet first, you can peel and press this label onto one side of your balsa sheet, and apply a blank label to the other side. Rub the label down onto the wood thoroughly, but not so hard that you leave ruts or gouges in the surface. Cut through the sandwich from the printed side, using a sharp #11 and a steel ruler, then seal the outer edges with thin CA glue (do not coat the root edge -- you need this edge raw for the white or yellow glue to sink in). If you have a multi-piece fin, you can still apply a solid-outline label after the fin has been cut out and assembled. You simply print two labels -- one in reverse -- and carefully apply them on each side. Seal with CA, and give the outer edges a buffing with 220-grit paper to smooth them off.

[jadebox]

I just finished a Comanche 3. The thought of sanding and sealing all nine fins was overwhelming, so I used the paper method. I used some heavy bond printer paper and 3M Super 77 spray adhesive. I sprayed the adhesive on the paper and stuck the fin to it. I then stuck that to another piece of pre-sprayed paper and placed the "sandwich" under a weight for a little while. Then I used a rotary cutter to trim away the paper. The rotary cutter worked much better than a standard razor knife. After trimming, I sanded the edges.

It worked well.

-- Roger
http://www.payloadbay.com/

[Gus]

Zeke,

I just finished building 6 Fliskits Acme Spitfires that use the label paper technique for both body tube sections and fins.

I modified the fin "skins" posted on the Fliskits website so they would cover all but the fin root.

I think the attached photostrip shows the technique pretty well.

First photo in strip shows label paper design cut to shape, backing removed, sticky side up.

Fin edge is placed into position (note that in this example the root edge is facing the top of the picture and will not be covered) and fin is then "folded" onto label paper to make nice crisp edges. When completely wrapped, any overhang on the root is trimmed with an exacto.

I have used this technique frequently on other rockets. It is surprisingly durable and allows for designs not possible with painting.

Once attached to the rocket, I spray everything with several coats of Rustoleum Clear. The clear coat creates a "shell" which permeates and bonds the label paper very well.

Be aware that you should check whatever clear coat you use to make sure it will not make the inkjet-printed label paper run (I've had that happen with some versions of Krylon clear).

Also, be aware that when the clear coat is added, it tends to make any white areas somewhat translucent so whatever is underneath will show through (fin grain). I sometimes paint the underlying object white (or use white tubes) before applying the label paper.

Have fun.

[zeke1312]

Thanks for all the info! I wondered how to handle the process of folding over the paper at each edge. In picture 3 and 4 on the Guss approach, there is an overlap on two sides. Is the overlap then cut parallel to each edge or the paper to be applied to the "up" side just laid over top the overlap?

How well does the self adhesive paper stick to the balsa wood? When painting, is the paper prone to blister in any of the processes described?

In any case, it sure looks like the paper method is superior both in strength and in producing a smooth surface.

I just finished a TLP Nike Ajax and the paper method sure would have helped!

Question: What are the advantages/disadvantages of self adhesive vs applying glue to paper, if any?

When Sandman makes his Nike Hercules model available, I'll use the paper process!

Thank you :)

[Gus]

Is the overlap then cut parallel to each edge or the paper to be applied to the "up" side just laid over top the overlap?
Just laid over the overlap. Looks fine, and way better than leaving the fin edges undone.

The label paper sticks fine to the balsa, but it does need an overcoat.

I've never had the paper blister.

[CPMcGraw]

...How well does the self adhesive paper stick to the balsa wood? When painting, is the paper prone to blister in any of the processes described?...

The self-adhesive labels stick well as long as they are rubbed down, and the edges are sealed so that they cannot pull up. The easiest way is with thin CA, which penetrates both the wood and the paper. Just remember to stay away from any root edges (fin-to-tube joints). You want the yellow (or white) glue to penetrate into the wood, and it cannot do this if it has been hit with the CA.

Blistering is usually a result of not firmly rubbing the paper down to the wood; it also happens when the label's adhesive is too old, or (if you're using plain paper with 3M77 spray adhesive) there isn't enough on the paper to adaquately hold it. If you see this happening before you've applied any primer, take a "T" Pin and poke a few tiny holes through the blister and apply thin CA. Let it wick through the holes and grab the paper from the inside. Press the blister back down before the glue "smokes", then sand the surface to eliminate any sharp ridges.

[Eagle3]

For my 4" diameter upscales I've either used 1/4" balsa laminated with heavy card stock or 1/8" ply cores laminated with 1/16" balsa that is then laminated with card stock. The card stock adds a lot of strength and eliminates a lot of finishing on the fins, i.e. no balsa grain to fill. I use thin coats of yellow glues and for each layer. I do both sides at the same time and wrap the fins in wax paper. Then I put them between two sheets of blue foam and throw a lot of weight on them for 24 hour min.

[CPMcGraw]

For my 4" diameter upscales I've either used 1/4" balsa laminated with heavy card stock or 1/8" ply cores laminated with 1/16" balsa that is then laminated with card stock. The card stock adds a lot of strength and eliminates a lot of finishing on the fins, i.e. no balsa grain to fill. I use thin coats of yellow glues and for each layer. I do both sides at the same time and wrap the fins in wax paper. Then I put them between two sheets of blue foam and throw a lot of weight on them for 24 hour min.

Buzz,

Something I tried many years ago while building a foam-cored wing was to put down a layer of glue (white, in this case) onto the foam, and a layer onto the wood. Let both dry completely. Note, this was actually something of an accident: I had originally glued the wood to the foam wet, and it never cured even after two days. This was a seven-foot wing with a 12" chord. The moisture from the glue remained trapped under the balsa. I used a MonoKote iron to evict the moisture and "polymerize" the wood to the foam. The wood diffuses the heat enough not to melt the foam, but it does liquify the glue enough to fuse them together. This was twelve years ago or more, I still have that wing, and not one inch of wood has pulled away from the foam. No weights needed. Once the glue "sets" again, it's done.

You could do the same with cardstock-balsa-cardstock sandwiches, just keep the glue layers thin to avoid excess moisture build-up.

[Eagle3]

I put the fins between foam with weights mainly to avoid fin warping due to uneven drying of the glue. The yellow glue has always dried well for me, but since you can never count on the glue drying evenly I take measures to prevent warping. The fins for my Maxi Marauder are super strong and very light.

I forgot to mention it earlier, but another reason I use the 1/4" balsa or 1/8" ply 1/16" balsa sandwich is to get better scale appearance rather than just use 1/8" ply alone or G10. Those thick fins just make them look BIGGER. *LOL*

[ScaleNut]

I like 3m spray and printer paper, I have not had as good results using products that shrink, like white or yellow glues , dope ect..

If the fins are to be cut out for a scratchbuild or clone, I laminate the balsa stock first than cut out the fins, this makes them easy to mark with a pencil.

I don't worry about the edges, they are easy to fill . I prefer to wick thin ca onto the edges after cutting out the fin. it seems to sand much nicer into a rounded edge that way .

the ca also helps seal the edge of the paper.

I've found there is a very definate strength advantage to paper laminating .

good luck with it

[Eagle3]

I may try this with my Qmodeling Rogue fins. The trailing tips of the fins look like they will snap off way too easy due to the grain direction. Some paper reinforcement should help prevent that.

[Bob H]

There is always the self stick label paper.

I have used it on a couple of builds lately and it sure speeds up the finishing process and the fins are much stronger. I get the plain white 8 1/2 X 11" label paper at Staples.

Just make sure you don't get the label paper marked "removeable" because the glue is not sticky enough.

[pdooley]

i have a problem when bonding regular printer paper to balsa with yellow wood glue.
the paper wrinkles.
am i using too much glue or should I switch to a 3M spray product?

BTW, I am applying weight after gluing, but the paper wrinkles almost instantly.

[gpoehlein]

i have a problem when bonding regular printer paper to balsa with yellow wood glue.
the paper wrinkles.
am i using too much glue or should I switch to a 3M spray product?

BTW, I am applying weight after gluing, but the paper wrinkles almost instantly.

Most likely, yes. First, I would switch to white (Elmers) glue for doing this - it dries clear and it dries a bit differently. Second, apply a small bead of glue across the fin in a zig-zag pattern and then spread it with a piece of cardboard or an old credit card. Once you have the fin covered, press down with the edge of the credit card and squeegee across the fin. The layer should be so thin it will dry in seconds. Immediately put your paper in place. Repeat on the other side of the fin and weight down with a heavy book to keep everything flat.

You might also try getting some full-sheet (8x10) label stock (Avery sells some). Because it is peel-&-stick, it will stick well to the fin, but will not cause any warping or wrinkling. Coat and paint as normal.

Greg

[pdooley]

my technique was a finger smear, which didn't remove nearly as much glue as a credit card squeegee.
i will try white glue laid thin.

regarding adhesive backed paper- I always thought the balsa is too porous to allow a good bond.
does label paper stick as well as glue?

[gpoehlein]

Yup - it sticks fine. I've done it on my Maxi Alpha, although I haven't had a chance to paint that bird yet. The label stock works great.

Greg

[Bob Kaplow]

my technique was a finger smear, which didn't remove nearly as much glue as a credit card squeegee.
i will try white glue laid thin.

regarding adhesive backed paper- I always thought the balsa is too porous to allow a good bond.
does label paper stick as well as glue?

I gave up on self stick paper for rockets back in original Gyroc days. The paper stuff didn't last very long before it started peeling off.

For spreading glue, F&F, epoxy, or whatever, they sell plastic squeegees that work well, or you can cut up pringle or other plastic lids and make your own. Credit cards are too stiff.

[STRMan]

I have been using self stick paper for a few years now and not one of my rockets has had any peeling problems. I think the trick is in the finishing.

I use CA on all but the root edges too.

When painting, it is important to do so SLOWLY. First, make a light, and I mean LIGHT, dusting of primer. Then another. Then another. No heavy coats of paint, so the solvents won't work through the paper and attack the glue. Once properly primed, it can be painted in an normal fashion without any issues.

[luke strawwalker]

What I've been doing is cutting the fins out, sanding them all to the same size/shape (stack-n-sand) and then individually rounding the front edges, and if I want the trailing edge tapered go ahead and do that too-- all shape sanding finished.

Then I lay a fin on a sheet of printer paper and make an oversize outline of it, and cut the outline twice that size, in a large 'double oval' shape (depending on the fin shape) I then put a thin layer of white glue on one side of the fin and place it carefully on the paper, with the leading edge facing the center 'dividing line' between the two oversize paper wrap halves. I flip it over and carefully roll the paper down onto the fin (make sure it's on something that any glue worked out around the edges won't mess up if it gets on it) and once the first side is smooth, flip it over on a clean spot and apply a thin layer of white glue to the dry side of the fin, then, while gently pulling the paper taut I fold the leading edge over to glue the paper to the freshly glued fin side. I flip the fin over and carefully work from the leading edge to the trailing edge, making sure any excess glue is worked out and that the paper is laying flat and smooth. Inspect both sides, and put it under a few books or other flat heavy stuff to hold it 'pressed' until it's dry, usually overnight.

Once it's dry, I carefully trim along the root, trailing, and fin tip edges to remove the excess paper. With this method, there is NO SEAM along the leading edge, which gets the 200 mph+ slipstream trying to rip the paper off the fin, and minimizes the seams and corners where the paper will inevitably try to 'lift'.

I haven't tried this with Super 77 spray adhesive yet but I plan to. The results are really good and pretty easy to do! Hope this helps! OL JR :)

[Mark II]

I haven't tried this, but I was just thinking that if you sealed the balsa first, and then glued on the paper, you would not have to worry about the moisture in the glue causing the wood to warp. I'm not sure that you would need to get too fancy with the sealing, either, since you would not be applying a finish directly on top of it. Perhaps spraying a couple light coats of clear coat onto the fins would be enough?

You could also laminate the fins with very thin sheet styrene, too, like 0.005" or 0.010" thick sheet. For that, you might want to use slow-cure CA as the adhesive. The slow-cure is supposed to work well for laminating layers of material together, especially plastic to wood. It also won't cause any warping of the wood.

Mark \\.

[Bob Kaplow]

I haven't tried this, but I was just thinking that if you sealed the balsa first, and then glued on the paper, you would not have to worry about the moisture in the glue causing the wood to warp. I'm not sure that you would need to get too fancy with the sealing, either, since you would not be applying a finish directly on top of it. Perhaps spraying a couple light coats of clear coat onto the fins would be enough?
Mark \\.

Then you're gluing the paper to the sealer, not to the fin itself. If your glue is stronger than the sealer, this is not a good idea.

If your sealer is stronger than the glue, well, then build with the sealer :)

[Mikus]

What I've been doing is cutting the fins out, sanding them all to the same size/shape (stack-n-sand) and then individually rounding the front edges, and if I want the trailing edge tapered go ahead and do that too-- all shape sanding finished.

Hey JR, are those pics from the new digital camera? :p

I've used contact paper in the past on some of my fins. It might be a bit heavy but it sticks well and is strong, like bull. ;)

[Mark II]

Then you're gluing the paper to the sealer, not to the fin itself. If your glue is stronger than the sealer, this is not a good idea.

If your sealer is stronger than the glue, well, then build with the sealer :)
Well, it was the thought that counts, right? :p Really, it was just an idea, but you're probably right.

I was thinking that if the builder applied a very small amount of the right kind of sealer, it would soak in and not just coat the surface. That's what seems to happen to the first 7 or 8 applications of Aerogloss, for instance, whenever I use it. (Brushed on full strength, too.) :rolleyes:

Are there any sealers that don't adhere as well as paper and glue to bare balsa? If so, does anyone even bother with them? :p Does the glued paper adhere better or even as well as an application or two of primer (i. e., the usual way to finish fins)? And are there a lot of builders out there who have the paint peeling off their fins because it can't adhere, due to the fact that they applied sealer to the balsa first? :eek:

Mark \\.

[luke strawwalker]

Hey JR, are those pics from the new digital camera? :p

I've used contact paper in the past on some of my fins. It might be a bit heavy but it sticks well and is strong, like bull. ;)

Nah, not yet... :) Those are old build pics from my Zooch Disco-Thor... taken with the cell phone... :eek: OL JR :)

[luke strawwalker]

Well, it was the thought that counts, right? :p Really, it was just an idea, but you're probably right.

I was thinking that if the builder applied a very small amount of the right kind of sealer, it would soak in and not just coat the surface. That's what seems to happen to the first 7 or 8 applications of Aerogloss, for instance, whenever I use it. (Brushed on full strength, too.) :rolleyes:

Are there any sealers that don't adhere as well as paper and glue to bare balsa? If so, does anyone even bother with them? :p Does the glued paper adhere better or even as well as an application or two of primer (i. e., the usual way to finish fins)? And are there a lot of builders out there who have the paint peeling off their fins because it can't adhere, due to the fact that they applied sealer to the balsa first? :eek:

Mark \\.

Anybody tried painting the sealer on and then wrapping the paper around the fin using the sealer as the glue?? Eliminate a step and save some weight at the same time... :)

I've never used sealer so I'm not sure if this is even possible... just thinking out loud... :) OL JR :)

[Gus]

I gave up on self stick paper for rockets back in original Gyroc days. The paper stuff didn't last very long before it started peeling off..
Bob,

I think it's time to give the label paper another try. I'm betting the adhesive used today is quite different from what it was in Gyroc days. I have dozens of rockets covered with label paper designs and not one has had any peeling problems. I don't use it to try to add strength, just for finishing considerations.

And there is honestly no need to make the process complicated.

All you need to do is stick the label paper to the fins and spray clear coat over it in several coats. I've never bothered gluing the paper edges and as long as I'm conscientous about applying enough clear coats to make sure the fins are "shelled" I've not had a problem.

The six Acme Spitfires noted in this thread from 3 years ago have not had any peeling from either the fins or body tube wraps (except the one that spent 3 months in a tree :( ).

My most flown label paper finned rocket is my "Goodbye Kitty" (http://www.rocketreviews.com/reviews/all/goodby_kitty.shtml) which I've probably flown 20 times. The fins on this one were front and back label paper with unglued edges (the black fin edges were just black sharpied). In spite of the complex contour of the fin edges there has never been any peeling, either front or back, or on the label paper body tube.

The same is true of my "BerthaVostok" (http://www.rocketreviews.com/reviews/all/berthavostok.shtml) which has flown at least 15 times. Again, the label paper on the fins is not of the fold-over type I did on the Spitfires, and it has held up just fine.

Honestly, there's just no need to over-complicate the process. Simple works just fine.

[pdooley]

Gus, that Kitty rocket is awesome!
Makes me wish I had a daughter! :D

[Mikus]

Anybody tried painting the sealer on and then wrapping the paper around the fin using the sealer as the glue?? Eliminate a step and save some weight at the same time... :)

I've never used sealer so I'm not sure if this is even possible... just thinking out loud... :) OL JR :)

I tried it once using thin tracing paper and Aerogloss sealer. It did not go well and I abandoned that idea. :o

[Mikus]

Goodbye Kitty? Awesome, I give that the coveted 4 chuckles!!!

:chuckle: :chuckle: :chuckle: :chuckle: