New varnish on a 60 year old boat

[Carl Schaefer]

I'm refinishing a 60 year old Penguin woody. While sanding down the old varnish the other day, it occurred to me to ask whether the new varnishes are compatible with what they used 60 years ago. Is there a certain varnish product line that is best to use when overcoating old, but refinished, varnish? I am sanding down the varnished interior using 60 grit paper, working my way up to 150 or so. Is this OK or do I really need to completely strip using a chemical peel? I really would like to keep the old patina of the internal ply and white cedar (or is it spruce?) frames. (I have, however, completely stripped the thwart, mast partners, sheer rails, etc.) Also, I assume that products like Armada are probably not compatible with varnish - is this so?

[ 12-18-2004, 07:33 PM: Message edited by: Carl Schaefer ]

[Captain Pre-Capsize]

If you asked the Antiques Road Show they would tell you that it will be worth $3,000 when done with it.

But if you hadn't taken off the original finish it would be worth $44,000!!!! ;)

[Carl Schaefer]

Originally posted by Captain Pre-Capsize:
If you asked the Antiques Road Show they would tell you that it will be worth $3,000 when done with it.

But if you hadn't taken off the original finish it would be worth $44,000!!!! ;) :eek:
That would be nice, wouldn't it? But as one of my good friends, who also owns a Penguin, is oft to say; "it's just a Penguin, fer chrissakes! There are 10,000 of them out there!". I want to balance my desire (and my limitations as a novice) to restore this to pristine condition with my desire to sail her as soon as possible. She will look great when I'm done and I'll be proud of my work, but it won't be a piece of art like much of what is regularly posted on this forum.

[Wild Wassa]

If you remove all of the old varnish that's flaking, cracked, crazed, oxidised or just generally sick, that should be adequate if you can rehydrate the old varnish that has been left.

60 years ago the medium would have been a traditional oil based varnish (or a painter made varnish, just as likely and heavy in oil), so I’d be inclined to use a similar product, over the top of a well cut (keyed) surface, if you are not going to wood the surface. I'd put extra oil in the top coats to aid hydration, as any old, underlying layers, will draw oil from the top coats (over time) as they attempt to rejuvenate themselves.

The real problem with leaving the old varnish on the surface is that the oil will have dried out somewhat. Oil based materials gain their quality because the oil doesn't dry out or drys out very slowly. The medium remains somewhat hydrated. This is how the oil based materials maintain their flexibility. Top coats crack when they have been deprived of oil or insufficient oil was added (if it was needed).

Modern varnish is a poly/oil blend base, I do not know how it would take (longevity wise) compared to rehydrating old varnish with a traditional material that's heavy in oil. I'd expect no dramas with a traditional varnish. I don't see much that could really go wrong with a poly oil blend though, if the surface is clean and uncontaminated. The inclusion of poly in the oil/poly material aids flexibility.

Blending the values (unifying the density of the old colour) can be difficult, try to do it early in the painting, rather than after your perfect top coat has been applied. It will be easier to unify the surface gloss, if tones are corrected early, rather than doing repeated touch ups afterwards which can result in a patchy surface gloss.

A traditional varnish can be applied like this, as they're a thick medium to begin with.
Dilute the first two coat with 50% solvent, the next two with 40% solvent, the next two with 30%, and perhaps the top two at 20% and then 10% . This will give you a process called 'thick over thin' or 'fat over lean' so that the uppermost layers are the most saturated with oil for when the lower layers drag out the oil. Another way of achieving 'thick over thin' is to apply, more oil per layer as you paint your way to the top (preferred but slow in setting). I like a refined linseed or a triple refined linseed, rather than a par (pale) boiled linseed, as refined linseed has less artefacts in it. You can increase the oil content per layer in combination with progressively reducing the solvent (per layer) as well.

Adding oil adds to the drying time but will give the same result (roughly) and give more of a long term flexibility to the emulsion.

If you are going to use a oil poly blend varnish, just keep putting it on straight, then maybe add a touch of oil to the top coats. See what your manufacturer's data sheets say about thinning or adding oil (or binder) to an oil/poly blend varnish. Some are so thin, straight out of the tin, they are not much thicker than water.

Good luck.

Warren.

[ 12-18-2004, 11:04 PM: Message edited by: Wild Wassa ]

[Carl Schaefer]

Warren,

Thanks very much. That helps immensely. Is there a particular product such as Z-Spar that I should use? I also wanted to mention that I replaced a cracked frame with a new one made of spruce that I bought from Aircraft Spruce and Specialty. However, when varnished it will still look very out of place with the darkened patina of the other frames and the internal Douglas Fir marine ply. I was thinking of "aging" this spruce piece with a mahogany filler stain that is compatible with the varnish I'll be using. Is that a wise move or is there another method to match these pieces?

Thanks, Carl

[N. Scheuer]

Speaking of Penguins, anyone looking for a spruce mast and boom for a Penguin might want to e-mail me.

Moby Nick

[Mrleft8]

Originally posted by Carl Schaefer:
Warren,

Thanks very much. That helps immensely. Is there a particular product such as Z-Spar that I should use? I also wanted to mention that I replaced a cracked frame with a new one made of spruce that I bought from Aircraft Spruce and Specialty. However, when varnished it will still look very out of place with the darkened patina of the other frames and the internal Douglas Fir marine ply. I was thinking of "aging" this spruce piece with a mahogany filler stain that is compatible with the varnish I'll be using. Is that a wise move or is there another method to match these pieces?

Thanks, CarlInstead of "aging" it with mahogany filler. you might try using a slightly thinned solution of Zinsser's amber shellac. You'll have to scuff the shellac before you varnish over it to get a good bond. Try it on a test piece first of course. If you still aren'y getting the color you want, ad a bit of burnt umber universal tinting agent to your varnish. Once again.....Test piece first! I've been told that varnish over shellac is a really bad idea, but I've never had any problems with this, as long as the shellac is thinned out and allowed to dry completely.

[NormMessinger]

Waren, you used the term hydration several time. Are you refering to water molecules?

[TimothyB]

http://www.kirbypaint.com/

Although they don't say so on the site, they do sell oil based varnish, and George can help you with any prep advice you need.

--T

[Buddy]

I have had problems with songle part polyurethanes lifing up in areas the second or third year ( on a covered boat) when applied to well sanded oil varnish. So, I myself would limit my choices to old school oil varnishes alone. And oil pigment from mixing tubes, or scraped out of settled soilds in old cans of oil stain, can color and blend that same varnish wonderfully.

[Carl Schaefer]

Originally posted by N. Scheuer:
Speaking of Penguins, anyone looking for a spruce mast and boom for a Penguin might want to e-mail me.

Moby NickDon't need a mast or boom but I am looking for a used wood or fiberglass centerboard -- know of any for sale?

Carl