Papering Fins and Bubbling

[mh9162013]

I've just used an old hotel room access card as a squeegee. Works great for me.

That would work well, as would an old credit card. The problem is setting it down, then the glue gets on your paper, paper towel, etc. So I wanted a tool that I could set down without getting glue somewhere I didn't want.

 

[mh9162013]

Update:

Here are the fins for testing. "Regular" uses the method described in my original post. "Double Glue" uses a similar method, but I added glue to just the balsa and let it dry before papering the fins. I will report back after exposing these to very warm air for a significant period of time.

 

[bjphoenix]

I've just used an old hotel room access card as a squeegee. Works great for me.

I forgot- I use one of those too. I put the glue on the balsa and spread it around with my finger. The I wipe my finger off and wipe off most of the glue with my finger, wiping it on a tissue each time. I put the paper on then use the key card as a squeegee on top of the paper to both push the paper down into the glue and squeeze out any excess glue.

 

[Kabulrocks]

Papering with Avery labels suffers none of these problems. It is so much easier. If nothing else, it might be a much easier technique to start with.

There are definitely circumstances when the *additional* strength (label paper *does* add considerable strength on its own, but not as much) of glued paper is necessary or desirable; I did it myself in one particular instance. But for the vast majority of the time, it's labels for me.

I've been wanting to create a video show exactly what I do, but don't have a suitable camera setup. Maybe I'll do a tutorial with photos, although a video would be much more useful in this instance. Will ponder.

How does the adhesive on the Avery label material hold up long term, or at least for a rocket lifespan? Asking because I have seen many Avery label on file folders fall off, however, they were several years old before failure.
Is there any advantage to sealing the fins with shellac and sanding smooth before labeling? Seems like the shellac would provide a nice non-porus surface for the label to stick to. Thanks!

 

[mh9162013]

How does the adhesive on the Avery label material hold up long term, or at least for a rocket lifespan? Asking because I have seen many Avery label on file folders fall off, however, they were several years old before failure.
Is there any advantage to sealing the fins with shellac and sanding smooth before labeling? Seems like the shellac would provide a nice non-porus surface for the label to stick to. Thanks!

I can't speak for @neil_w, but whether or not shellac works might be irrelevant because the whole point of labels is to save time and effort. All else being equal, if you're going to shellac the balsa before the label, why not just make a traditional papered fin?

I think the best way to answer your question will be to try it out yourself as I'm sure few people (if any) have used shellac before an Averay label on balsa fins.

 

[neil_w]

My oldest label-papered rocket is 9 years old. They are stored in my basement, so have not generally been subjected to challenging environmental conditions. In any case, no problems so far.

A smooth shellacked surface would indeed be excellent for label adherence, but as @mh9162013 says above it kind of defeats the purpose of low-effort papering.

My intuitive take, wholly unsupported by testing but consistent with my experience, is that:
1) if as much dust as possible is removed from the surface before applying the label paper, it'll adhere quite well to the balsa.
2) if the edges are properly sealed (and then covered with paint), it's a pretty stable sealed system. The edges can't left if they're all sealed down, and there's no way for air to get in.

Who knows, maybe at some point in the future my fins will all start peeling, but so far so good.

 

[mh9162013]

So the results from my way-too-small-sample-size test are in. The pictures below largely speak for themselves. You'll notice how the bubbling seemed to follow the grain pattern as it had in the past. The bubbling only occurred on one side of the regular papered fin, though.

Here were the testing parameters:

Fins were placed vertically (held with small clamps) in front of two small space heaters. The fins were exposed to air that was 16% RH at between 122 degrees and 136 degrees F. The total exposure time was about 13 hours.





Bottom line: If time is short, I'll use label paper. If I have enough time and want the maximum ASMR from my model rocket build, I'll use the double-glue papering method.

 

[Orestes Mayo]

Here's how I paper my balsa fins (for LPR and MPR builds):

1. Apply Elmer's white glue (school glue) or Titebond II to one side of the fin.
2. Use a custom-made scraper to coat the entire surface of the fin and remove as much glue as possible.
3. Apply the paper (basic, 20lb copy paper).
4. Set between two sheets of wax paper and that on top of one textbook and under about 3-6 textbooks (about 25 lbs-ish)
5. Let dry for several hours (or overnight).
6. Use a knife to cut away the paper around the fins.
7. Repeat steps 1-6 on the other side of the fin.
8. Coat the edges (but not root edge) with thin CA
9. Sand edges

The above steps have worked pretty well the past few years, but during a few of my last builds (BT-60 sized rockets with larger fins - Patriot, Red Nova and Green Eggs), I've noticed some bubbling of the papered fins. These bubbles are roughly oval in shape and are parallel to the balsa grains. These bubbles also only showed up when the rockets were stored (not yet painted or primed) upstairs in a low-humidity and warm environment (think 20-30% RH and 75-85 degrees F).

Initially, I figured that my bubbling was due to not using enough glue (or using a different type of glue), but that can't be it, as I didn't do anything different for these past few kits from the earliers kits. After some discussion and thinking, I believe my bubbling is due to one or more of the following variables.

1. Larger fin size. Instead of spreading glue around an Estes Wizard fin, I'm spreading it around the fin of an Estes Green Eggs rocket. The larger fin size means more time is spent spreading glue around. This means more time for the glue to dry and soak into the balsa before the paper is placed on top. With less glue bonding to the paper, bubbling is more likely.

2. Inconsistency in the balsa. The glue is soaking and bonding into the balsa at different rates due to the heterogeneity of the balsa wood's grains. This means the balsa fin surface doesn't bond to the paper in a consistent fashion.

3. "High" storage temperature. Keeping these fins in an environment that's warmer than where they were papered (storage = about 75-85 degrees and papering took place in about 65-70 degrees) meant any trapped air and/or water in the balsa had a greater chance to expand or evaporate more quickly and increased the risk of bubbling. I'm confident this is an important factor because one set of fins bubbled while being stored in the dryer and warmer environment for a few weeks. However, before going into this environemnt, it was stored in a cooler (55-65 F and 30-50% RH) environment for 3+ months with no bubbling.

I wanted to share these thoughts because based on my research here, people get seemingly different results when papering fins and bubbling despite using largely the same methods. Yes, the type of glue and amount of glue added to the fins are important variables (and the obvious ones). But I think there are other variables at play, such as temperature differential, speed in which glue is added to the balsa and balsa wood inconsistencies.

My take away (so far): I need to add more glue to larger balsa fins to make up for greater air drying and possibly more time for the glue to seep into the balsa. But I can't add too much, then I risk warpage and paper wrinkling. So how do I address this uncertainty? Build more rockets!

Hello. I also paper my fins but I use shipping labels, no wood glue. Originally, I would CA only the edges to keep the paper from being affected. I had noticed some occasional bubbles when I primed. I resolved it by applying CA on the flat side of the fins too. Yes, I do have to sand lightly but the result is a smooth finish and super strong fins. I use this on my LP, MP and HP. No bubbles.

 

[4regt4]

My oldest label-papered rocket is 9 years old. They are stored in my basement, so have not generally been subjected to challenging environmental conditions. In any case, no problems so far.

A smooth shellacked surface would indeed be excellent for label adherence, but as @mh9162013 says above it kind of defeats the purpose of low-effort papering.

My intuitive take, wholly unsupported by testing but consistent with my experience, is that:
1) if as much dust as possible is removed from the surface before applying the label paper, it'll adhere quite well to the balsa.
2) if the edges are properly sealed (and then covered with paint), it's a pretty stable sealed system. The edges can't left if they're all sealed down, and there's no way for air to get in.

Who knows, maybe at some point in the future my fins will all start peeling, but so far so good.

Working in an office environment for many years, it seems to me that the label paper usually used on file folders is different than the recommended Avery product I use. I'm speaking about the glue itself. The Avery product has a glue that is REALLY sticky. I tried peeling it off of a balsa scrap, and I damaged the wood trying.

As Neil_w pointed out, the really critical step in using label paper is making sure that all sanding dust is removed. I cover the fin in blue tape to remove the dust, and if it comes off too easily (it often does), it's necessary to do it again.

Hans.

 

[aerostadt]

Working in an office environment for many years, it seems to me that the label paper usually used on file folders is different than the recommended Avery product I use. I'm speaking about the glue itself. The Avery product has a glue that is REALLY sticky. I tried peeling it off of a balsa scrap, and I damaged the wood trying.

I am currently using Staples 8 1/2 x 11 inch white shipping labels on my light weight depron wings for my latest Double Shuttle. It is very sticky, but if I am careful wrinkles are not a problem and the procedure is quick and easy. I do not plan to put anything on top of the paper labels.