The Unwanted Glassine Finish on Motor Mount Tube

[brockrwood]

There it is. The unwanted glassine finish I will now sand off so that my wood glue bonds nice and tight to the centering rings. This is a 24mm motor mount tube.

A glassine finish on any sort of model rocket tube is not needed, IMHO. It simply impedes the glue bond between parts. If a rocket tube will be filled, sanded, primed, painted, et cetera, what is the point of the glassine finish I am just going to sand off?

I am sad that Uncle Mike, of Uncle Mike’s Rocket Shack, got out of the model rocket business. All of his motor mounts were nice, rough finish tubes, which needed no preparation before being glued to centering rings.



A few wipes with the 600 grit sandpaper and that glassine finish is gone.

 

[lakeroadster]

Well... here's the deal... glassine makes for a pretty paint job and a smooth surface.

You sanded off the glassine... but because it was there... you have a nice smooth surface.

Prime a coupler, check out how it looks.... and get back to us.

 

[dhbarr]

Isn't it true you can also just wipe it off with a damp cloth?

 

[brockrwood]

Well... here's the deal... glassine makes for a pretty paint job and a smooth surface.

You sanded off the glassine... but because it was there... you have a nice smooth surface.

Prime a coupler, check out how it looks.... and get back to us.

I don’t need no steenking glassine finish. I have Elmer’s Carpenter’s Wood Filler, sandpaper, and wet sandable primer. I can make anything smooth.

On the other hand, @lakeroadster ’s models end up having a near flawless finish, so maybe I should just pipe down. ;-)

It wouldn’t be the first time piping down was the appropriate course of action for me. ;-)

But seriously. Shouldn’t I glue everything together when it has a rough finish and THEN make it nice and smooth?

 

[brockrwood]

Isn't it true you can also just wipe it off with a damp cloth?

This technique is unknown to me! I will try it!

 

[waltr]

I read about wiping it off with a damp cloth and it works very well and is quicker, easier than sanding which I also did before.

 

[caveduck]

I've always kinda hated the glassine coatings across the board. The glassine is just an artifact of the original tubes Estes could get in the 1960s. I've made ultra-finished competition and display models for many years, and the characteristics of the glassine just get in the way. For competition models I would usually just peel it off, slather the remaining kraft layers with CA and then go to my usual 2k epoxy primer/paint system. Overall I much prefer the newer more uniform all-paper white tubes that now come from Estes, BMS, etc. (BTW I think they were pioneered by Howard Kuhn/CMR way back in the 1970s) Because there is no discontinuity in material type, they sand more reliably and you usually don't need to coat them with CA. The CA treatment works great on coupler tubes too, I'll take up that coupler challenge!!

 

[rharshberger]

This technique is unknown to me! I will try it!

Yes glassine can be easily "modified" by using a damp cloth or sponge. Glassine is nothing more than paper that has been "supercalendared" aka run through high pressure rollers to flatten the surface and make it glossy. The damp sponge removes the glossy hard surface.

 

[brockrwood]

I will modify (narrow) my original proposition: There is no need for a glassine finish on a motor mount tube. For a motor mount tube, all I want is a very strong glue bond. A rough finish tube is best for that.

 

[bobbyg23]

Super easy to peel right off. Grab a corner on one of the ends and start peeling.

 

[Ez2cDave]

For competition models I would usually just peel it off, slather the remaining kraft layers with CA and then go to my usual 2k epoxy primer/paint system.

Dave,

Didn't that add a lot of extra weight, especially for something like a 13mm SD model ?

Dave F.

 

[caveduck]

Dave,

Didn't that add a lot of extra weight, especially for something like a 13mm SD model ?

Dave F.

Not unless some dense filler is used, because you sand nearly everything off and the 2k primer is very lightweight by volume compared to the rattlecan variety. The CA turns the kraft fibers into a composite and you can sand pretty aggressively. IIRC peeling the glassine layer would end up taking about 25% of the weight off a 13 or 18mm tube. Going all the way to a .75oz glass tube would cut the weight roughly in half. It gets you to where the motor casing at several grams is the heaviest item in the whole rig and air-picking dominates the performance. OK the last was definitely drifting off topic...anyway if you don't do something to it the glassine layer is only so-so smooth, even not counting the spiral gaps.

 

[samb]

...
A few wipes with the 600 grit sandpaper and that glassine finish is gone.
...

You provided the solution to the "problem" in post #1.

You may want to check out http://squirrel-works.com/ for glassine-less tubes and balsa nose cone goodness.

 

[jimzcatz]

Isn't it true you can also just wipe it off with a damp cloth?

Most definitely absolutely positively YES. no sanding needed, just a damp cloth or sponge. It doesn't take much to remove it. And peeling? Now that's funny.