Does wicking a cardboard tube with CA add any strength?

[Tim51]

Hi all
So is any increase in compression or shear strength gained by painting Loc tubing (stripped of glassine) in thin CA?
Stay safe,

 

[rharshberger]

Dont know if it adds much in the way of strength, but it does prevent delamination of the cardboard and makes it harder so it sands better, as well as imparting some water resistance.

 

[Tim51]

it does prevent delamination of the cardboard and makes it harder so it sands better, as well as imparting some water resistance.

Thanks yes that's my experience too - I actually like it as a material to work with - interested if any actual testing has been done regarding its actual Physical properties ; )

 

[jimzcatz]

The exact opposite, it's turns it into brittle phenolic.

 

[Mike Helm]

I never noticed imbrittlement or experienced any failures because of CA. It does keep the edge of your body tube neat and firm. I never did more than 1/8" around the end. Back in the days when we were using a lot of friction fit and masking tape thrust rings it was always important to keep our motor mounts clean because we didn't want to get our motors stuck or damage the motor mounts when inserting or removing tight fitting motors.

 

[richP]

Works best with the really thin CA, just make sure to do it outside, with the wind at your back, with gloves on, and safety glasses, and.....

I prefer to warm the tube a bit and just brush on some thin epoxy.

 

[rharshberger]

Works best with the really thin CA, just make sure to do it outside, with the wind at your back, with gloves on, and safety glasses, and.....

I prefer to warm the tube a bit and just brush on some thin epoxy.

Epoxy thinned with a bit of alcohol works well too.

 

[Tim51]

The exact opposite, it's turns it into brittle phenolic.

I consulted the Book of Faces on this, and a fellow club member made a similar point. His argument was that Cyanoacrylate resins cure brittle, so as CA impregnates the cellulose fibres of cardboard it makes them brittle as well. This process of CA wicking differs from fibreglass or carbon fibre composite layup, where the resin component (polyester or epoxy) surrounds the matrix of carbon or glass fibres but does not saturate or impregnate the actual strands of tow in the same way. I imagine that in those cases (like thin epoxy) where the material is not fully saturated, there is effectively two layers - an unwetted sublayer of ordinary cardboard, bonded to an epoxy hardened 'epidermis', so hopefully one gets the best of both.

 

[Speaknoevil]

I don't know, I do it on the edges and outside coupler surface. If you use the extra thin CA it evaporates before the whole coupler is soaked. Most of the inside layering of coupler is still cardboard, but you end up with a hard shell that you sand down smooth. As stated by @rharshberger it protects from dings and delamination.

 

[DRAGON64]

It is best used on cardboard to keep the fibers/layers of tubing from unraveling. It does ad a little strength to the end of the tube, but mostly it is used to keep the ends of the tube from tattering from nosecone and coupler insertion etc.

 

[JeromeK99]

When I first got back into model rocketry as an adult (BAR 1.0) I ended up launching with a large club in Southern California's high desert. My precious rockets were being ground down and destoyed by the harsh dry lake bed conditions. I started laminating my tubes and balsa with 0.75 oz fiberglass cloth and finishing epoxy. Done right, it adds very little weight but really makes the builds last. Larger MPR and HPR got a little thicker cloth and layers/wraps adeded.

 

[o1d_dude]

I don't know, I do it on the edges and outside coupler surface. If you use the extra thin CA it evaporates before the whole coupler is soaked. Most of the inside layering of coupler is still cardboard, but you end up with a hard shell that you sand down smooth. As stated by @rharshberger it protects from dings and delamination.

This is what I have done for years.

The best way I have found to do this is to dip a long handle Q-tip into the open bottle of CA and swab the area to be “case-hardened”. The Q-tip will harden if you work slowly so you’ll most likely need to have a good supply of them handy.

With careful work you can achieve a fiberglass like surface which begs the question...why not just use alcohol-thinned epoxy applied with a brush or cloth? I hear that works, too.

 

[Wally Ferrer]

Is there a guideline for thinning epoxy with alcohol? Or just add a few drops until you get the desired viscosity?

 

[CalebJ]

Can you use denatured alcohol to thin it?

 

[rharshberger]

Is there a guideline for thinning epoxy with alcohol? Or just add a few drops until you get the desired viscosity?

Not really, thin with denatured alcohol until it wicks into a piece of sacrificial tubing as a test.

Can you use denatured alcohol to thin it?

Yes, denatured alcohol is better than rubbing alcohol since it has less water in it.

 

[CalebJ]

Excellent, I have plenty of it already. One less thing to stockpile.

 

[Joekeyo]

Works best with the really thin CA, just make sure to do it outside, with the wind at your back, with gloves on, and safety glasses, and.....

Thin CA. The thing you hate to love.

 

[Culprit]

I've seen a few comments above about CA glues being too brittle in some applications, and setting too fast without wicking. I'm also a wood lathe turner, and enjoy making pens. A common finish on wooden pens is CA. Many pen turners liked the high gloss they can achieve through sanding and buffing, but found it too brittle and quick setting for use as a wood finish on an item like a pen. Someone connected to the wood turning community developed a CA glue that is much less brittle and stands up well to daily use in this application. It's not the cheapest CA on the market, but I figured I would mention it here since it may be of interest to some of you. The guy who developed it for woodturners has been very good about not revealing the formulation other than to say it does not achieve it's flexibility through the addition of rubber like other flexible CA glues on the market. I'm a mech E and not a chemist, so I have no clue, but it doesn't seem to affect bond strength. It's available in thin and medium.

Here is the description from tennesseepensupply.com, for what it's worth. Emphasis theirs:

Mercury's Flex CA is brand new and designed for pen turners and other wood working. Unlike other brands which use rubber to give their CA flexibility, Mercury Adhesives uses a unique set of ingredients that won't interfere with that crystal clear finish you've come to expect from Medium Flex is available in 2 oz Bottles and 8 oz Refill Bottles.

It has a longer open time and allows you to easily get a smooth coat on the pen blank. It gives a flexible finish which can survive abuse that customers do to pens. Mercury Flex CA is designed to be used with accelerator and needs it to cure "instantly". And, it goes on even smoother, provides better coverage, and helps give you the best finish for your pens and other turnings. Mercury's Flex CA can be left alone for a matte or satin finish, or it can be buffed & polished up to a glass-like shine. The Thin Flex CA gives a great base coat for your wood pens. By itself, it provides protection with a more natural feel than using medium. Remember, Mercury's Flex CA needs accelerator to begin curing quickly.

Mercury Adhesives manufactures their CA here in the USA, in Atlanta, GA. It is a medical grade CA that is highly concentrated and the purest premium CA available. For finishing pens, just a drop or two is all that is needed for each coat. There are additional formulations for pen makers. Thin Flex, Medium Flex, Thin Regular, Medium Regular, Odorless, & a unique High Performance that is great for oily wood. Another unique feature isn't with the CA, but with the bottle. Except for the jumbo 8oz refill, all Mercury CA is packaged in clog free bottles. There are three sealing points within the cap, including a steel pin to help keep the tip clear & open. But, if CA does build up on the tip or cap, just soak it in acetone for little while and it will be good as new.

Here's a desk pen I turned from locust wood finished in CA:



I have no connection to Mercury Flex or Tennessee Pen Supply - just passing on info from another hobby that may be of interest to some of you here.

 

[kevindcornwell]

I use MinWax Wood Hardener (bought at ACE hardware). It is essentially super-thinned (with volatiles - primarily acetone) epoxy that wicks into the fibers and then, over a few days, hardens. Over a few weeks even chipboard will become very hard and durable. Turns balsa into a hardwood (ok, just a tad of an exaggeration, but not much.) I bought a glass bowl with lid just for this use. I pour in the hardener, put the piece in and put the lid on. Let it sit for a 1/2 hour to completely absorb the product, take it out and let it sit a spell (pour the liquid back in the can). It does add a bit of weight as you're impregnating the wood with epoxy. It retains sufficient flexibility and does not become brittle like CA does.

 

[Speaknoevil]

I use MinWax Wood Hardener (bought at ACE hardware). It is essentially super-thinned (with volatiles - primarily acetone) epoxy that wicks into the fibers and then, over a few days, hardens. Over a few weeks even chipboard will become very hard and durable. Turns balsa into a hardwood (ok, just a tad of an exaggeration, but not much.) I bought a glass bowl with lid just for this use. I pour in the hardener, put the piece in and put the lid on. Let it sit for a 1/2 hour to completely absorb the product, take it out and let it sit a spell (pour the liquid back in the can). It does add a bit of weight as you're impregnating the wood with epoxy. It retains sufficient flexibility and does not become brittle like CA does.

Thanks for the tip. I have used it on wood. Never thought to use it on cardboard.

 

[KenECoyote]

In my limited exp with CA'ing body tubing using regular thin CA (I did this on some of my early small builds), it made the tubing more brittle and prone to cracking. I theorized that the pressure from the ejection charge would normally be fine for the untreated bt since it can flex and bulge a bit, but once I coated the bt, it became more brittle and couldn't take the pressure and instead fractured. YMMV

 

[Alan15578]

In my limited exp with CA'ing body tubing using regular thin CA (I did this on some of my early small builds), it made the tubing more brittle and prone to cracking. I theorized that the pressure from the ejection charge would normally be fine for the untreated bt since it can flex and bulge a bit, but once I coated the bt, it became more brittle and couldn't take the pressure and instead fractured. YMMV

Typical body tubes do bulge quite a bit under pressure. This can allow a lot of blow by past the seal on a piston tube. I put a layer of light FG around the tube. I recommend laminating epoxy, but I have used CA to save time, with no issues. The old Blackshaft tubes work best for this, and the inside can be sanded smooth. With Estes tubes, I have coated the inside with epoxy, but the sanding and reaming is too much work.

 

[neil_w]

Turns balsa into a hardwood (ok, just a tad of an exaggeration, but not much.)

Pedantry alert: balsa *is* a hardwood.

Carry on.