Originally posted by rbeckey
On rare occasion in this forum I have had information and opinions presented to me in ways that would seem intimidating to a less experienced builder. The point is that it is silly to insist that there is only ONE way to stick parts together in a more or less permanent fashion. I do not labor under the delusion that my way is the only way or even the necessarily the absolute best way. It does, however, work for me, and quite well, I might add. To discount any technique or point of view right out of the gate would usually be a mistake. Some people will try all and settle with one exclusively, others will use what suits them at the moment.
Powder: I did not put this here for you specifically.
Wow, rbeckey, did you really think I got mad or something? I'll have to tone down my sarcasm in the future.
Some of you guys have hit 'dead center' some of the weaknesses of water-based glues. Yes they can indeed cause local shrinkage as they dry, especially if you put them on in a heavy layer. So I don't. In fact, I usually water down my glue for just about every application, and use only a thin layer at a time.
I have never had these glues re-absorb enough water, even in a humid environment, to come anywhere close to getting loose again. I think you would have to literally submerge the assembly for a few days before the glue would get soft enough to be dangerous, and by then your cardboard BT and balsa NC will be ruined anyway. It may be theoretically possible, but I don't ever worry about it.
I don't like to use water-based glues to fill or cover balsa grain, because it takes too long to dry, it gets too messy for me, and because if you go through all that pain-and-agony, the coated balsa part does not take spray paint very well. I have had finishes craze and peel when put directly on white glue. You have to use a primer coat, and that means you have to lightly sand the exposed glue so the primer can get a grip.
One of the quirks of using water-based glues is that when you try to apply a thick fillet (like along fin roots) you will almost always get uneven drying, and probably some holes where the glue shrinks as it dries. If you put on a thick fillet, it usually dries with a raised ridge along the edges of where you place the glue (the edges dry first, and harden in place). Again, I only put on a light layer, and only do this a few times per fillet. If I want big, fat, swoopy fillets, I don't use white glue.
White glues (and for that matter, yellow glues, and epoxies, and all the rest) are heck to sand. You gotta be pretty careful to get it only where you want it, and to wipe up/off the rest, and to get it smooth before it starts drying. If you think you are going to fix it after it dries, you are mistaken. You will end up sanding away everything AROUND the dried glue before the glue itself begins to give way to your sandpaper.
One of the outstanding places I have found to use water-based glues is to water them down and lightly paint the insides of BT before assembly. This helps reinforce the BT slightly, but I do this mostly for other reasons: After the cardboard has absorbed the glue and dried, it is much more resistant to peeling at the edges, it is more resistant to charring from hot ejection gasses, and it assembles better. By this I mean, when you have to add a motor mount, you assemble the mount with centering rings and can easily 'dry' fit the mount into place (no hurry, there's no wet glue in the middle of things to worry about). Afterward, when you add a light bead of glue around the outer edges of the CR, it quickly grabs to the insides of the BT and makes a solid attachment. (Kind of like 'pre-glueing' the balsa fin roots) But you have to be careful to get the BT well dried out, or else you can have the NC start sticking in the front end (not good).
White glue is good for a lot of things------and it's not good for a lot of things.
Just Kidding!!!!
