What are the different thicknesses of CA good for?

I just started using CA a couple weeks ago. I have one bottle of thin CA, which, so far, I've used to stiffen the thin tips of some beveled fins on one rocket, and tried to use to fill the grain on the fins of another - went OK, but I can still see wood grain now that I've primed it.

But I'm not sure what other things thin CA is good for, and as far as medium and thick (and extra thick?), I'm not sure. I know that sometimes CA is used to tack fins in place while glue dries, but I don't know what thickness that is. And Google tells me that extra thick is for filling gaps (although I'm not sure when this is necessary, unless you accidentally get a gap somewhere you didn't want it - which I recently did).

So what are the uses of CA with regard to different thicknesses?

Super Thin is great for gluing fingers to stuff... :wink:


Sorry about the pause... computer froze while I was editing this post.

Thin is used to seal and harden balsa... Examples are sealing the edges of fins after papering, and making balsa look like plastic/glass.

Medium is slower to set, and used for gap filling and tacking things down. Examples are making fillets, filling holes, and tacking fins before epoxying them.

I've never used thick.

Oh, Off Topic... Make sure that you don't use the wrong brand of clear spray paint.

HTH
Jim

Agree, i had such a hard time with it. I only use it once, now I only use the thick CA. But am interested in what uses for thin CA, other than sticking your fingers to stuff.

My answer was meant to start as snarky, but go on to really be helpful. Damn browser froze and I lost my post, just I as I hit save.

I keep some of the small tubes of gel CA (Dollar Tree, Walmart) in my range box for field repairs. Not so much for gap filling but because it stays where I put it, as opposed to thin CA that just runs like mercury as soon as I take the cap off.
In my experience, thin CA by itself will not fill balsa grain. It's too thin ! Strengthen, yes, but follow up with wood filler, bondo, spackle, filler/primer... (pick your poison) and sand/fill/sand...

I tend to be dubious of anything but thin CA. Cyanoacrylate is actually really weak in bulk, prone to brittleness. Where it shines is bonding two closely-mated surfaces in tension. If you're trying to do gap filling, CA is simply the wrong glue for the job.

Most of the time I use CA for tacking parts before attaching with epoxy, plus hardening balsa. I can understand difficulty handling the thin stuff... my advice is to use the tiniest amount you can -- a drop or less.

Zeroignite said:

I tend to be dubious of anything but thin CA. Cyanoacrylate is actually really weak in bulk, prone to brittleness. ...

Click to expand...

I agree, CA is not the best structural adhesive for most rocket building. Quick repairs and hardening thin wood parts, yes. Oh, and when called for in kit instructions and endorsed by the kit designer... Aerotech Barracuda... medium CA.

Thin CA is good to put a drop around a drill hole or cut end of a cardboard tube. It is thin enough to wick into the cardboard. This makes the hole or edge of the tube less likely to tear, crumble, or be damaged by the constant fitting together of parts. However, on the end of a tube, the CA will penetrate the cardboard, but cause it to swell, so you will need to sand things down.

Medium is good for tacking things in place until the big adhesives come out. Thin is just too runny to stay in one place, you will glue your hand to the tube before the fin is tacked in place.

Thicker stuff is used as regular glue by people in a hurry and lacking a rocketry glue selection.

I mostly us regular and thin CA, but when the surface is very porous or not perfectly flat, thicker CA is best used. The Gorilla Super Glue is a thick CA, even though they don't specify it as such on the packaging, formulated with rubber to make it much less brittle and, thus, much more impact stress resistant. Hobbytown USA hobby stores sell an even thicker rubberized CA that's MUCH cheaper per unit volume than the Gorilla CA ($4.99 for 4 oz.) called Foam-Cure that's made for EPP and EPO (both CA safe foams) foam aircraft, but I suppose it would be good for other purposes. Curing of the thicker CAs can be accelerated with accelerator "zap" spray. Another technique is to spray one part with the accelerator, let it dry, then press it against the other part which has the CA on it.