Water proofing

[Dave R.]

I'm going to build the superstructure of the Okahumkee from
balsa wood; mostly 3/32. I'm concerned with moisture from my "Foggy" as
well as pond water.
What do y'all suggest I water proof with? Weight is an issue.
Thanks,
Dave

[Spankbucket]

How's about good, old-fashioned dope?? Works fine for me.

[andy]

if weight is a problem, take the balsa hull as a positive modell and create a CFK hull.

Andreas

[Dave R.]

Thanks Bernie, will nitrate dope be enough to proof against water or
will I need a coat of butyrate dope as well?
Andreas, the problem is the big boxy superstructure. (see, Okahumkee Standard Gauge, thread)
The files mention shellac, has anyone tried this?

Dave

[Spankbucket]

I've been using nitrate dope as butyate isn't easy to get here in the UK but unless someone knows otherwise I don't think there is any substantive weight difference and I think butyrate is for inflammability on model aircraft??

My 'Queen of the Esk (Josie Olsen)' model has an extensive balsa superstructure all coated in nitrate dope, first clear coats then white.

[derekwarner_decoy]

Andreas ...please ...what is CFK........ I  do not know it in OZ.....Derek

[mjt60a]

I always use sanding sealer (because I read an article in a magazine once that recommended it), apparently it's nonshrinking cellulose dope with talcum powder mixed in, the talc is to help fill any grain in the wood so it gives a very smooth finish but as that may not be a problem in the case of these models I suppose dope by itself would work perfectly well.

[scotfriend]

Hi PD's,

what i have tired is to soak the Balsawood with thin superglue, the strength  is increasing and after sanding the then rough surface you can use spray can filler. But if you do it it is best to go outside because the smell is really bad and take care to your fingers do not glue them to the balsa.

regards Hans

[jelley_baby]

I like mjt60a use sanding sealer, which is easy to get and not too expensive, and my father before me use to swear by sanding sealer as a grain filler, I have also use modern acrylic varnish to seal grain where I intent to paint after.

Regards Graham

[steamboatmodel]

Thanks Bernie, will nitrate dope be enough to proof against water or
will I need a coat of butyrate dope as well?
Andreas, the problem is the big boxy superstructure. (see, Okahumkee Standard Gauge, thread)
The files mention shellac, has anyone tried this?

Dave

Hi Dave,
We had one fellow in our club that used to make paper mache hulls that he coated is shellac. He worked mostly in static models, but did have a couple of RC boats that worked quite well.
Regards,
Gerald.

[Dave R.]

Thanks Hans, the super-glue idea might make it bullet proof as well , but I think the size of
this superstructure would make it cost prohibitive. It's rectangular, about 24x8x6 inches.

The local hobby shops don't carry nitrate dope; it seems no one is building stick and tissue
air planes anymore. They have butyrate, though the cans are covered in dust. China and ARF*
products have brought the art of model building to grief.
 
I would need to go to Orlando for dope so I'll try the sanding sealer from the corner hardware store first.

If the hw store carries shellac, I'll do a test piece of balsa with that, as well.

Any other ideas, while we're on the topic?

Dave

*Almost Ready to Fly

[Spankbucket]

I too can recommend sanding sealer as a primer coat on balsa. Dope can then be applied over it .

[David Hunter]

My local model shop recommended a product called EZE-KOTE, a laminating and finishing resin for balsa & foam by Deluxe Materials. Reading the back of the bottle it did not mention anything about being waterproof but it is model aircraft fuel-proof!  It was expensive but then what isn't these days. I bought some

I will report back when I employ it.

David

[mogogear]

Andreas ...please ...what is CFK........ I  do not know it in OZ.....Derek

CFK - hull in carbon fibre with epoxy resin 

I had to look it up myself