When is it necessary to re-varnish spars?

[mhorowit]

Last summer my IA gave me the OK to cover my wings. I've been giving the spars a glance everytime I pass them and wondering if there is any need to re-varnish them. Is there any criteria for determining if they need a new coat?
- Mike

[Pearson]

Re: When is it necessary to re-varnish spars?

Mike,

Since no one else has expressed any opinions or experience with determining how to tell when the spars need refinishing, I'll chime in with my 2 cents worth.

You have already done the best thing that could be done to determine if your spars need refinishing. If your IA gave you the green light to recover, that means he feels the spars are good like they are. As a trained professional, I would call him and discuss the pros and cons of refinishing the spars. If they really don't need it, that would be time and money you could spend on some other area.

Unless you have reason to doubt his judgement, an IA with eyeballs on your project is your best source for determining what to do next. If you do doubt his judgement, find another IA.

[Robert Lees]

Re: When is it necessary to re-varnish spars?

Bear in mind it might be another 20 years before the fabric next comes off enabling a full-length inspection of your spars.

Is the existing varnish good for that potential length of time?

[crispy critter]

Re: When is it necessary to re-varnish spars?

Mike,if the fabric is off it's time to scuff and varnish. Why would you not want to put an extra coat on while it's apart?

[Dennis Keels]

Re: When is it necessary to re-varnish spars?

Mike:
Kevin is right after all the work what is a quart of varnish and a little time.

[N96337]

Re: When is it necessary to re-varnish spars?

Yup... get those buggers varnished now...it'll probably be your last chance! I like Polyfiber's Epoxy varnish...but any of the good "spar varnish" products will be fine.
JH

[mhorowit]

Re: When is it necessary to re-varnish spars?

Bear in mind it might be another 20 years before the fabric next comes off enabling a full-length inspection of your spars.

Is the existing varnish good for that potential length of time?

I can't make that judgment because I don't know the purpose of varnish (unless it's to keep water out) and I don't know how to evaluate the existing coating. Suggestions welcome - Mike

[mhorowit]

Re: When is it necessary to re-varnish spars?

Mike,if the fabric is off it's time to scuff and varnish. Why would you not want to put an extra coat on while it's apart?

Because if it's extra work and I don't need to I have enough other issues to work. If I were to re-varnish you weren't thinking of removing the ribs from the spar were you? - Mike

[crispy critter]

Re: When is it necessary to re-varnish spars?

No Mike,not unless there are ribs that need to be removed. Just take a scotch brite pad or maybe even some mid# sandpaper and scuff all the wood surfaces you can get to. Then you can take a foam brush or paint brush and put a coat on or two on. You can even use a paint gun to spray it if you want,just make sure you thin it good enough to go through the paint gun and DO NOT use the same gun you plan to spray dopes,primers,&paints with. I also like Polyfibers 2 part epoxy varnish(that doesn't mean you will then have to use the polyfiber cover process).
If you want to send a few pics of your spars we can probably advise you a little better on weather to varnish or not. However in my opinion,I would not put fabric over any wood without re-coating the varnish.

[mulwyk]

Re: When is it necessary to re-varnish spars?

Mike:
haven't seen you around the forum in awhile. Good to have you back.

At one time (like 50 years ago) it was SOP to re-varnish the spars everytime the wings were re-covered...maybe every 4 years with cotton/dope. But the cover you're putting on (Stewart's?) will last 5 times as long, so it's 5 times as important to varnish now, while the cover is off.

Varnish protects the wood. Varnish is the reason there's still plenty of old T-craft flying around with 70 year old wood spars.

I use 100 grit sandpaper, very gently, on old varnish. You could use 220 grit if you think you might get a little heavy handed. The idea is to sand just enough to provide a "tooth" for the new varnish coat to follow. Unless you find areas where the varnish is flaking off, you're not actually trying to remove the old varnish, a very light sanding will do.

I'll second the polyfiber epoxy varnish. Great stuff.

No need to remove the ribs, varnish right up to them then stipple a bit (poke with the end of the brush) to work varnish into any spar/rib gaps.

It's a messy job, but goes a long way to preserving the plane, and it makes the spars beautiful again. When you're done you can stand back, admire your work, and give yourself a pat on the back. Set down the brush first.

[Robert Lees]

Re: When is it necessary to re-varnish spars?

70 year old wood spars...

Mine are about 150 years old!

Think about it

[mikeg]

Re: When is it necessary to re-varnish spars?

Hey, the wing is open. Varnish the spars. Better to do it now than wish you had.
Mikeg

[mhorowit]

Re: When is it necessary to re-varnish spars?

Mike:
haven't seen you around the forum in awhile. Good to have you back..

Oh, I've been around; usually scowling at the 4' of snow covering my fuselage and keeping me inside!

At one time (like 50 years ago) it was SOP to re-varnish the spars everytime the wings were re-covered...maybe every 4 years with cotton/dope. But the cover you're putting on (Stewart's?) will last 5 times as long, so it's 5 times as important to varnish now, while the cover is off.

Varnish protects the wood. Varnish is the reason there's still plenty of old T-craft flying around with 70 year old wood spars.

I use 100 grit sandpaper, very gently, on old varnish. You could use 220 grit if you think you might get a little heavy handed. The idea is to sand just enough to provide a "tooth" for the new varnish coat to follow. Unless you find areas where the varnish is flaking off, you're not actually trying to remove the old varnish, a very light sanding will do.

I'll second the polyfiber epoxy varnish. Great stuff.

No need to remove the ribs, varnish right up to them then stipple a bit (poke with the end of the brush) to work varnish into any spar/rib gaps.

It's a messy job, but goes a long way to preserving the plane, and it makes the spars beautiful again. When you're done you can stand back, admire your work, and give yourself a pat on the back. Set down the brush first.

That's a good approach; I'll do it - Mike