Is balsarite nitrate dope?
 

Does anyone know what exactly is balsarite? Is it actually just nitrate dope?

I am building my first scale kit. Prior to covering, I read that balsarite is recommended to seal the wood. I can't find this stuff here, so am looking around for a substitute.

Will normal wood lacquer works too?

Chris

Is balsarite nitrate dope?
 

You do not need Balsarite to seal the wood. As far as I am concerned Balsarite is pure cr#@. You didn't say how you were going to finish the plane. If you are using iron on covering all you need is a smoothly sanded surface. You can use some cheap hair spray to help raise the grain and then give it a final sanding. Balsarite will muck up the surface and is almost impossible to sand. If you have evere tried to recover a plane that has this junk on it, you will curse it forever. About the only place Balsarite can be used IMO is around the engine bay.

Vince

Is balsarite nitrate dope?
 

Vince,

Thanks for the reply. I am planning to use silkspan or silk - is there a substitute for nitrate dope? How about lacquer found in the hardware shops?

Chris

Is balsarite nitrate dope?
 

If your planning on using silk, dope can be obtained from several of the homebuilt aircraft suppliers. Wicks Aircraft and Aircraft Spruce are a few of the better ones. Also you might give some consideration to a high quality water based clear polyurethane.

Vince

Brodak Dope
 

Chris,
You may want to take a look at Brodac's line of dopes, primers and fillers. I have been using them for a few years now and can vouch that they are a far cry better than Sig and Aerogloss. It is a Mill Spected product that has not changed since the thirties. Flows nice from an inexpensive touch-up gun. Most of the time it is sandable in thirty minuts and with a clear coat, glosses out like a mirror. One layer of mediun and a top layer of lite silkspan and it is tougher than plastic covering and repairs without a visable trace. Check them out at: http://www.brodak.com/
Good luck,
"Geppetto"

Is balsarite nitrate dope?
 

Thanks guys for the info.

Is the polyurethane mentioned similar to the Tamiya PS polyurethane topcoat?

R/c stuff is hard to find here .... so I am looking for substitutes all the time.

Chris

Is balsarite nitrate dope?
 

Go to your local Home Depot or similar and look for Minwax water based clear polyurethane, works great and it cleans up with water. Hint add a few drops of food coloring it makes it eaiser to see where you have covered.

Is balsarite nitrate dope?
 

One of the purposes of nitrate dope is to shrink the fabric.

Does Polyurethane varnish shrink like dope?

Is balsarite nitrate dope?
 

It will shrink tissue, silkspan, and silk but none of the synthetic fabrics.

Is balsarite nitrate dope?
 

Too cool -- I played with the stuff on some spinnaker cloth (which is very lightweight nylon), but had no luck there. I'll have to get out some natural fabrics and resume the experiment.

BTW, water-based polyurethane can be colored with the tints they use for latex paints. I got somebody [don't want to get anyone in trouble for doing the impossible]... got somebody to supply me with some tinting colors from the store where I bought the Polyurethane. They were told by the department manager that those colors couldn't be mixed with the stuff and instructed not to mix it for me, but they did manage to liberate a film can of each of a couple of colors for me and it seemed to mix just fine at my house.

PS -- if anybody can give me pointers on getting a good finish with fabric that won't shrink for me, I'd sure love to hear 'em. Spinnaker cloth is beautiful and amazingly light stuff that comes in a bunch of vibrant colors with its weave already sealed... I just haven't been able to get it to cover an open framework without sagging.

Is balsarite nitrate dope?
 

I have been using the polyurethane with tissue to cover balsa sheeted airframes, works great and it's very light and cheap.

Is balsarite nitrate dope?
 

What's Balsarite good for in the engine bay? Fuel-proofing? I got some to help the Monocote stick better where it wraps around the cheeks of sport planes. I never can get the monocote to stick there worth a darn on the end-grain.

Is balsarite nitrate dope?
 

That is about the only place I even consider using it.

Vince

Is balsarite nitrate dope?
 

RE: Balsariteing to get covering to stick to your cheeks...

Wow, I don't seem to have sticking problems on any of the places where I really stretch the covering (like the cheek cowls and wingtips).

I don't know how much difference it makes, but I usually sand those parts to at least 360 grit (sometimes to 600) and blow out the dust -- though I suspect that a tack rag is a better idea. How do you do your sanding etc. before you cover?

____________________
Of course you are, my bright little star...
I've miles and miles of files, pretty files, of your forefathers' fruit
And now to suit our great computer... You're magnetic ink!

Is balsarite nitrate dope?
 

This one was just too easy.........Im gonna pass. <grin>

Vince

Is balsarite nitrate dope?
 

SAND???????? WHAZZAT?????????

Is balsarite nitrate dope?
 

Ain't that what the kids play with on the beach???

Is balsarite nitrate dope?
 

Sand the cheeks? 220 grit then an air blast from the compressor. Hey.... Fine sandpaper and a tack rag? Hmmmm..... :idea:

Is balsarite nitrate dope?
 

CaptKAOS -- LLLLLLLLLLLonnnnnnnnnnng Time no see! Is Misery -- er, I mean Missouri -- far enough from Roslyn to escape Them?

Oh, back to the balsarite, my balsa is seriously smooth when I put on the covering (doesn't feel fuzzy or anything at that point) so I figured that getting it to that point may be making a difference in how the covering sticks (yeh, wherever I stick it, smart guys!)

Is balsarite nitrate dope?
 

Balsarite WILL help iron-on covering to stick. It works. It is not really necessary in most cases, though. You need to put a LOT of it on an area like a firewall in order for it to be fuelproof. One coat is not.
It has absolutely nothing to do with covering with silk or silkspan, and should be nowhere near. Neither should polyurethane.
Do it right. Go out and get some nitrate dope. Sig sells it. Use the nitrate to attach and fill the silk, then finish with butyrate. Nitrate is much stickier than butyrate, and fills much better. It's not fuelproof, though. I think the reason a lot of people find silk and dope difficult is they do not know about nitrate.
And check out the Brodak butyrates. They work categorically better than the Aerogloss stuff. Do NOT attempt to use aerogloss white or yellow. You will be sorry.

So.....no, balsarite is not nitrate dope. Don't try to use a substitute, not laquer or anything else. It might end up being totally incompatable with whatever you use next to prime and paint. Don't reinvent the wheel, here. You could end up totally ruining your model. Cover it with nitrate dope. Prime it with Pactra Prep or Brodak dope based primer.
Check out my gallery page, and see that I do a lot of silk and dope and know what I am talking about...good luck!

Is balsarite nitrate dope?
 

Easytiger, is the Midwest dope compatible with the Pactra dope? I.e. can you use the thinner from one with the other?

I remember using Nitrate years ago on stick and tissue. It was really easy to work with.

I picked up some Aerogloss to paint some 1/2 C/L trainers. I think I got yellow for the bipe trainer. I'm crossing my fingers. :eek: Is it sprayable?

Thanks for all the great info.

Is balsarite nitrate dope?
 

I have not used Midwest specifically, but I have mixed Brodak, Sig, Aerogloss, even forty year old Kempel dope with no ill effects, with the one caveat being nitrate may NEVER go over butyrate. Butyrate over nitrate, no problem. I think you should be okay.
The problem with Aerogloss white and yellow is that the pigments they use are transparent automotive pigments, and they need a ton of coats to cover. That's not the end of the world with a solid balsa 1/2a CL trainer, but it could easily add an ounce of paint to the plane. I would spend three bucks and get some Sig or Brodak. Preferably Brodak. You will get a good finish in two coats instead of ten. If you prime the thing white or silver first, that really helps, too.
The darker colors of Aerogloss are not a problem at all.
People from way back remember Aerogloss being great stuff in the fifties, but the formula has changed over the years. I have used NOS stuff from back then, it smells different from the new stuff. I only have dark colors in the NOS, so I cannot say if the white was any better back then.
But Brodak(and to a lesser extent, Sig) is like night and day.
Any of them are sprayable.
I did a scientific little mercury a few years back. Took about fifteen coats to get a decent yellow finish with aerogloss. Came out heavy. Gloss ended up being deep and nice, though.
Did a Yellow Aircraft A-4 Skyhawk with Aerogloss white...after at least ten coats, I was STILL not satisfied with the finish.

Is balsarite nitrate dope?
 

Nitrate dope will not shrink silkspan or silk. Nitrate dope is used to glue the covering to the wood, and to fill the pores of the fabric. Nitrate dope will not shrink the fabric, and it is not fuel proof. I suppose you could use Balsirite to stick silk on with an iron, but why would you do that and have the silk come off the next time it is in the hot sun? Butyrate dope is used after the nitrate dope to shrink the fabric and to provide a fuel proof finish.

If you use silkspan be prepared to recover and paint a year or so later.

Is balsarite nitrate dope?
 

Nitrate will shrink the stuff, but only a little. I use water to shrink, then seal it with nitrate, because it only takes a coat or two of nitrate to seal the tissue or silk, rather than several more of butyrate.

Good point about the durability of silkspan. You WILL be recovering your plane if you use silkspan over open bay framework. Over sheeted surfaces, no problem. It saves weight over silk. Over open bays, though, it pays to use silk. A little more weight, but MUCH more durable.

Is balsarite nitrate dope?
 

Thanks, now that you mention it I do recall having been told that Butyrate is the shrinkier dope... although I also know that nitrate will shrink more with a hotter thinner (i.e. if mixed with something liek acetone as compared to something like MEK or lacquer thinner).

BTW, I use micafilm, so I have experienced Balsarite but I have not experienced it coming loose in the sun. (Granted, I live in a relatively cool climate, but I've also had my sailplanes in the car for days at a time, so they would have experienced heat well in excess of 100 or 110 degrees there repeatedly and for several hours at a shot, but the covering never came loose.)