# How to coat a tube with CA?

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What is the best method for coating the surface of a tube (inside, outside, or both) with CA? Do you pour in a puddle and roll it around, pour some in a pie tin and roll the tube in it, or what?

David Erbas-White

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I don't usually coat the whole thing, just 1" inside from the edge, the edge, and whatever drips onto the outside. I drip/pour it on as I'm rotating the tube (don't do this over your shoes, or the carpet). On the inside a puddle forms and you walk it around. On the outside it will very quickly go to the lowest point (right above your shoe).

Joel. phx

And the question made me think of my Calculus class. What was the name of the cone that had an infinite surface area but a finite volume. You couldn't paint the outside but if it was clear, you could fill it with paint to color it.

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Just the inside. I dribble a little into one end, then use a dowel or strip of wood to smear it as I rotate the tube. Then I swap ends and repeat the process.

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I've tried both, even used a small paint brush but mostly, I manage to glue my fingers to the tube. ; )

Depending on the inside of the tube, it can act like a wick and coat itself with enough of a flow, as you rotate it.

Randy

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That's been my experience too. I always use thin CA too.

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It strengthens the cardboard--aft end to prevent landing damage (if the rocket design is susceptible to this), forward end to prevent zippers.

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I guess I also forgot to ask the obvious question: and the point of doing this is... (to increase tube strength, to protect against hot gases, to waste CA???)

The reason for the question is I just received a kit that has one doing this at various parts of the assembly process, and I haven't done it before.

David Erbas-White

David Erbas-White wrote:

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Excuse the newbie question, but what's the purpose of this? (I mean, from responses it's obvious that it's done commonly enough, I just don't see what it's supposed to do.)

-- Carl D Cravens ( snipped-for-privacy@phoenyx.net) Wichita, Kansas, US -- Read my model rocketry journal at

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I use the "drip it on and roll tube around" method with a "quick and smooth" wipe of a folded paper towel when necessary. Watch out for towel "soak thru"; my fingerprints now identify me as "Bounty".

May I ask why you are coating entire tubes? I've done it many times with homemade and scrap tubes to increase their stiffness, but it is now something I look to avoid, if possible.

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The CA soaks into the fibers and stiffens the paper up, sort of a faux phenolic. Thin CA is really needed for this to get maximum absorption into the fibers. It does make parts stiffer and stronger. I use it to make paper fins.

I have noticed one thing, tho; the soaked paper seems to transmit heat more readily than plain paper. I have some min diameter homemade body tubes which I soaked in CA and they bubble the paint just forward of the motor. The plain paper tubes don't.

Anyone else see this in a CA soaked tube?

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Gives some bulk (strengthens) the tube. On the aft end of a motor tube, you're constantly banging the edge as you install and remove motors. On plain cardboard, you might find it becoming out of round, bent, or the layers separating. The CA prevents that. Some thing for the nose end bodytube and aft bodytube on fast recoveries. Some say it helps the bodytube cut the elastic shockcord faster :o

You will find if you need to sand the inside for any reason (piston perhaps?) it mades a sandable surface that doesn't have those 'frizzies' like after sanding plain cardboard.

Joel. phx

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Sorry, I didn't mean to imply I was doing the whole tube (although in one case I am, but it's a very short tube ). I have the new Triatomic kit from Essence, and they have several points in the instructions that recommend coating an inch or so of the tube with CA.

David Erbas-White

Gary wrote:

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It also acts as as a very good fire retardant when staging. It worked really well on the 3 stage Saturn V, no scorching.

Randy

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Drip a drop inside the end and roll it around, holding the tube near horizontal... add more if needed as it soaks in, until you have a continuously wetted ring.

-dave w

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THe secret is in the last step:

Now carefully peel your fingers from the tube...

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

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Minimum diameter tubes readily transmit motor casing heat to the paint, fin/body glue joints etc. regardless of coating them with CA or not.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

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Makes sense to me on plain cardboard. I'm use to using the different CA's in my RC world but never thought to use them in rockets. I wonder does anyone use this method on phenolic? I have not had much success using CA's in the past with these tubes. I have always used epoxy.

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I actually give this treatment to just about every rocket I build these day. I coat the inside tube surfaces with thin CA at places where I want extra durability - such as the forward tube opening, the body tube forward of the motor mount (ejection charge protection), and the entire motor mount tube. CA treatments like this will tend to affect the fit of adjoining parts, but a quick touch-up with 400grit sandpaper is all that's needed.

I've tried the "puddle & roll" method, but don't like it because the puddle tends to travel along spiral lines. Instead, I uncap the CA bottle and use a cotton swab to apply it. If needed, I tape the swab to a chop stick for extra reach.

Dave Virga NAR 77896 L1 Black Forest, CO Colorado Springs Rocket Society -