The Big Finish

 The Thrifty Rocketeer blog continues...

A couple of weeks ago, I spotted a small volume of "Sanding Sealer" on discount from a major rocket distributor and parts supplier. Since I had a few cents in my pocket, and I was placing another order anyway, I went ahead and pulled the trigger on this.  I figured I would learn a little bit about it and perhaps use some on a larger project down the road, when finish appearance was important to me.

Well, I've already learned a bit.  Not all of it was good, but life is a journey... and so, I'm on a learning curve regarding this stuff.

First, the amount was only a couple of fluid ounces, which is fine by me, cause the square inch area of my balsa fins and nosecone are usually quite small to begin with.

But perhaps we should back up to the beginning.  It's my understanding that a rocketeer or modeler wants to seal the pores of any wood so that it will not absorb the paint unevenly and reveal the wood grain beneath the finish.  That's the goal.

Now, some guys use CA (super glue) to do this, and other's buy a gallon of "wood sealer".  But my first advice was to make a slurry of wood glue and a couple of drops of water.  After thinning down the wood glue, one "paints" it onto the wood surface and lets it dry. It will raise the grain in the first application.  So sanding is required.

The second application will fill in some of the gulf and cracks left by the first sanding, and by the second sanding, the surface is markedly smoother.  By a third application, the surface should be very smooth and rock hard... basically ready for either primer or paint.

I understand the process for using sanding sealer is basically the same.  Coat, sand, re-coat, sand smooth....

But while I had this understanding, I was a bit surprised there were no instructions with the jar when it arrived.  Oh, the label had been custom printed with the company name, but there were no details of the chemicals involved.  There were simple instructions on the back label, including instructions to brush it on and wait 60 minutes between coats.   

So, I launched into the process with a disposable brush.  It didn't matter that it was disposable, as I found this product is/was water soluble, and washes out of a brush quite easily.

Then I read something on line that made me question if I was using this right.  Someone remarked about sealing their rocket, OVER the final paint job.  It occurs to me that this sealer might be intended to preserve and protect a paint job.  So I resolved to ask on-line about the proper use.

Boom.  I got as many responses as there were other opinions about how to create a fine finish. But most all said "sanding sealer is for sealing wood" and all contained instructions to coat, sand, re-coat, re-sand, until the surface was smooth enough for me.

So this last holiday, I started an involved rocket that featured five smaller nose cones, one large balsa nose cone, and five fins.  All of which could be sanded and sealed.  So I started with this new sanding sealer, and set the wood aside to dry. I figured it would take an hour or two to dry before I could flip the fins and coat the other side.

To my amazement, I found that the fins I started with were almost dry, as I finished coating the various nosecones (which I could do on all sides before setting on end to dry).  This means I could almost immediately flip the fins one at a time and coat the second side.  Within another 10 minutes, everything was dry and it was time for some light sanding. I chose 220 paper because that's what I had on hand. It worked well.

Very shortly, I had a second coat of sealer on all the nosecones, and the fins were sanded and drying from their second coat.  This stuff was drying amazingly fast. I barely had time to wash out my brush under the tap before I needed to use it again.

Now, here's a downside:  My wife complained that she was smelling varnish or something at the kitchen sink.  So I ran some more water down the drain and removed the drying brush from the window ledge over the sink.  Husbands beware: Wives don't like chemical smells in their kitchen!

After everything was sealed and sanded and smooth, I finished installing them in the various rocket tubes and glued them in with wood glue.  It was then that I started thinking about the next step, painting.

I noticed that each of the wooden nosecones had an amazingly good-looking clear coat and the wood underneath was rather attractive just as it was.  It occurred to me that either I was going to have to prime the entire rocket, nosecones, fins and all.... or that they were going to have to be masked... a very laborious process.  It also occurred to me that I should have considered pre-painting the nosecones or the body tube pods before gluing them onto the main body... simplifying the painting process.   Ah well... a lesson for future builds, I suppose.

But the point of this entry was how GOOD the sealed wood looked, even before painting.  The natural wood, while not really appropriate for a model rocket, looks sharp against the flat white body tubes of this model.  Except for the "still exposed" body tubes and paper cardboard tubes, I might be temped to fly it as is.  However, part of the idea of painting is to preserve and protect those cardboard parts from dew, mist, humidity and water.  And that's one reason why we paint. (There are others as well.)

So, while I don't know a lot about this "Sanding Sealer" and the lack of instructions is a little annoying, now that I know how to use it, and how good it looks,  I can consider it in part of the paint and design process in the future.

One downside:  While the small jar (about the small size of a cold-cream jar or small Vic's vapor rub jar) has a screw-on lid, there seems to be a little seepage of the product into the threads, every time you open the jar.  As a result, there is a bit of build-up in the screw-on threads of the screw top.

The jar will still screw on, but the process of closing up the jar becomes harder and harder with each use.  I have also found that a fingernail run around the lip of the jar and around the threads can easily remove this build up, but it is a constant process, and you should get to it while the product is still soft.  The longer you wait, the harder the residue.

And note, I did not wipe my brush off on the lip of the jar. This was all from product flowing down off the inside of the jar lid into the threads on its own.

Perhaps one could put a layer of Saran Wrap over the jar when first opened and then again when closed, to help slow or defeat this penetration, but that almost seems like more trouble than it is worth.

I'd love to hear your suggestion on what you do to combat this leakage, and which product you find most helpful to seal your wood. 

This has been the Thrifty Rocketeer reminding you to "Close up your glue and sanding sealer" so that it doesn't dry out!