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[Brian60]

Not having used balsa for the last 50 years I've bought some! It's 2mm thick sheet and while gluing it is not going to be a problem, I would like to know how to seal it and make it stiffer.

Surely something better than the ubiquitous model plane dope must have come along in all that time?

[Colin Bishop]

There are several alternatives although some would say the original is the best but dope is a bit smelly. An excellent waterbased sealing resin is Deluxe Materials Eze Kote https://www.deluxematerials.co.uk/gb/rc-modelling/82-eze-kote-5060243900746.html

Alternatively a thin finishing epoxy resin will do the job.

Of course the old traditional finishes of sanding sealer, varnish or oil based primers still work too, but Eze Cote or Epoxy will take just about any finish over the top.

Colin

[david48]

I don't know if it would work but how about Ronseal wood hardener . It's used on wood work that's a bit soft starting to rot so it's easer to paint .
David

[Colin Bishop]

I have heard of Ronseal wood hardener being used. It might work but I would prefer to use the proper stuff intended for the job. The Ronseal works best with damp wood so may not be the best choice for dry balsa. Using the correct stuff is a no brainer really.

Colin

[inertia]

http://www.modelboatmayhem.co.uk/forum/index.php/topic,7710.0.html
From Reply #8 onwards.
Update on suitable abrasive - use silicon carbide finishing paper available from several suppliers - I use this one http://www.toolbank.com/0/p/FAIARS115180
Like it says, this is not the only way but it works.
DM

[Brian60]

Thanks for the ideas guys. I've used the ronseal on  a wet rot window frame a few years ago. From a spongy wet mess in 24 hours it was rock hard and impervious to water and although sandable afterwards was extremely tough.

I think I'll give it a try if I can source some over here.

[BFSMP]

This is something I do know about having used it many times on small projects such as nativity scenes and model dolls houses for my family.

The best way of hardening and sealing balsa wood is to use cellulose sanding sealer and cellulose thinners in multiple coats.

Start off by using a 25/75% mix respectively to give the thinned out sealer chance to impregnate the very open soft grain on the wood, gradually inverting the mix after numerous coats to a 75/25% mix respectively.

After each couple of coats rub down the wood with a fine wire wool to reach a very hard and mirror finished piece of timber.

However be prepared to paint on at least 10 coats to gain a superb finish of perfection.

Jim.

[Umi_Ryuzuki]

Several coats of satin finish laquer work.
Also Laquer, tissue and then laquer. We have built many warship hulls using this method.
Lay down a coat of laquer, then work the tissue onto the wet laquer and wet brush out the air bubbles. Then continue down the hull and the next side.