[GZG] Working with Balsa

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d afternoon--

There are (or used to be) "sanding sealers" out there. I remember using
something called "Seal & Sand" on Pinewood Derby cars when I was a kid (nearly
40 years ago now). My recollection of it is that it was
varnish-like.

If you can't find a purpose-formulated sealer, the most inexpensive
varnish you can lay hands on might serve. I'm planning to use a fair bit of
balsa myself for the United Stars Navy, and am going to try what I've
described.

Best, Ken

> --- On Sun, 9/7/08, emu2020@comcast.net <emu2020@comcast.net> wrote:
From: emu2020@comcast.net <emu2020@comcast.net>
Subject: [GZG] Working with Balsa
To: gzg-l@vermouth.csua.berkeley.edu
Date: Sunday, September 7, 2008, 2:18 PM

Hello all, Â I am reaching out to the group for some help with using balsa
some custom ships I'm doing. I am having a problem in the finishing because
invariably there is a wood grain that shows through the paint. Is there a way
to effectively seal the finish model that will allow me to give my completed
models a smooth finish. I am trying to avoid switching to plastic card and
such as I find it difficult to work with and less versatile than balsa, not to
mention more expensive. Â Thanks, Â
Eli_______________________________________________
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> 2020@comcast.net wrote:
That could be a problem. It's been decades since I worked much with balsa, but
I don't remember sealant being available in spray form. It may well be now,
but spray "paint" tends to be thin, whereas you're looking to fill the grain,
which either needs something thicker (and
thus requires brush application) or is going to take a /lot/ of coats to

get a properly smooth finish, possibly requiring sanding down between each
coat to avoid altering the shape of the model. I'll happily be proven wrong,
but those are my recollections from messing about with balsa (for model
rocketry) once upon a time.

Phil

> I am reaching out to the group for some help with using balsa some

I've used Sanding Sealer in the past for model rockets. You brush it on,
let it dry and sand it smooth and it might take 2-3 coats for a very
smooth finish. This may be a problem if your ships have areas that are hard to
sand.

Here is the one I have seen on shelves locally:
http://www.hobbylinc.com/htm/mid/mid71-1.htm

Something you could do is basic hull out of balsa, sealed and sanded, and then
details out of heavy cardstock (thin cardboard like a cereal box) or
plastic/metal bits.

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re's a auto base coat called filler that is a lot thicker than regular mini
base coat. It might work.

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ling the basic structure might work well, in fact. The basic shapes are mostly
geometric. I use balsa because it is also easy to pin details to the wood by
simply sticking them in with a bit of glue. a sealing coat should make this
impossible. I would have to be careful about the glues I used to glue surface
details on, however.

-Eli

-------------- Original message --------------
From: "Star Ranger" <dean@star-ranger.com>

> > I am reaching out to the group for some help with using balsa some
or
> plastic/metal bits.

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The traditional material is "sanding sealer", usually a clear
nitrocellulose varnish-like coating that serves two purposes: 1) To
fill the grain. 2) To raise the "nap" of the wood surface and make it brittle
and easy to sand smoothly without tearing.

You should be able to get it at any DIY/handyman/woodworking shop,
although you might need to buy a litre or so. I used to be able to
get it from model-shops in small tins back when I used to build balsa
and tissue model aircraft, but I haven't been in one for years so I don't know
what's available now.

However you only *really* need to use sanding sealer if you're going to apply
a clear finish, which is unlikely if you're building model spacecraft.
Assuming you're going to paint, any white acrylic undercoat will do. Apply a
coat (no need for a spray, any brush or roller will do), let it dry
*thoroughly*, and sand until the undercoat is only left in the grain. Repeat
until the desired finish is achieved, and then apply a final coat and sand
*lightly*.

If you are making your parts from flat sheets of balsa, you might
want to consider doing your grain-filling and sanding on the entire
sheet, *before* you cut out your parts. Consider also undercoating and sanding
parts of the ship before assembly.

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big problem is that I discovered this issue after the initial prototype models
were built and assembled. Sanding the models would be near im[ossible at this
point. The main bodies of the ships are made from the thicker square rod or or
rectangular cross sectioned blocks. This allowed me to bulk up the design
quick.

This is all valuable info that I am cataloging for the next batch. I
learned a lot on the initial build-up.

-Eli

-------------- Original message --------------
From: Robert N Bryett <rbryett@gmail.com>

> The traditional material is "sanding sealer", usually a clear