How to avoid really dark varnish?

[Howie]

Well, it's happened again. I strip the old finish (with Dad's stripper), clean & brighten with Messmer's Part A & B, and all the wood is a nice golden light brown. Then I apply the varnish (Epifane High Gloss Clear) thinned 50:50 with their thinner and zap - the wood immediately turns dark dark brown - almost black. It's been 20 hours now & its brightened up a bit, but still...!

This happens every single time I varnish old canoe wood (white & red cedar). Sure, the canoe is 70+ years old, but it looked great before the varnish went on. Anybody have a clue what's going on?

I assume it's because the varnish is thinned so much that it soaks right down deep into the wood - which is a good thing I guess. I'm on a well system here but the water is well softened, and can't hardly be but a teeny trace of salt in the water from the softener. Come to think of it, the water did make the wood darker until it dried off, but thinner alone caused the wood to be darker still.

Makes me wonder why I bother to clean & bleach!

 

[Jan Bloom]

Wood oxidizes deeper then appearance. Personally I prefer the old oxidized color and go to great length to simulate that look when replacing pieces of planking. Most 2 part wood bleaches are an oxalic acid solution and hydrogen peroxide. As you have tried a 2 part bleach I do not know of any thing else on the market that will give you a lighter surface.

 

[Howie]

It's just so odd that the wood looks nice & tan prior to varnishing. I'm thinking the only way to keep that color is to not allow the varnish to penetrate. Which isn't good for the wood I'd guess. Epifanes varnish may be touted as 'crystal clear' but it contains tung oil which I've found can seriously darken wood. Ah well... It is looking better as it dries.

 

[Andy Hutyera]

Too late now, but perhaps an initial coat of a water soluble varnish might prevent what you are observing. I only used it once on walnut and was surprised to find that it did not darken the wood at all. I don't know if there would be any adhesion issues arising by following up with a good quality spar varnish like you are using. Perhaps a little experimentation is in order. An intermediate coat of shellac would likely assure good bonding between the two varnishes.

 

[Jan Bloom]

Fresh sanded wood has a lot of "air space". When something "wet" is applied that "air space" is filled and the wood surface will change in appearance and darken. The amount of change is somewhat dependent on the wetting agent. All wetting agents will darken the surface to some extent. Even "water white" finishes will darken the surface as the air is displaced. Water based "varnishes or lacquers" are no different. Walnut being a dark wood to begin with may not show the darkening as much as a lighter wood. However, I would find no change unusual and not in the realm of my experiences. I have been building, repairing and restoring stringed musical instruments for 45 years. The water based "varnishes and lacquers" are no different, they fill the pores and microscopic scratches replacing air. If one wants to see what a piece of wood will look like with a "water white" finish then wipe the wood with a dampened rag. Epifanes varnish is not a "water white" varnish and will by its very nature darken wood, new or old, bleached or unbleached.

 

[Howie]

Interesting. Thanks all. I'm guessing that having the varnish seep deep into the wood trumps all. I believe cedar is a very oily wood when new, and this oil is what causes it to be rot resistant and pliable. When it ages I'm guessing these oils seep out. This leaves pores - the 'air space' Jan speaks of - that the thinned varnish loves to wick into. Makes sense. I'm consoling myself by thinking I'm doing the wood good. I also glop on a coat of thinned linseed oil on the outside for the same reason - that also darkens the wood tremendously.

BTW, I did try using shellac layers between varnish layers at one time. The shellac dried extremely quickly so I was able to complete the job in no time. Not sure what went wrong but about a year later I noticed adhesion problems between the layers in places. I don't use shellac any more!

 

[Fitz]

I am not sure how dark, is dark for you. You make it sound very dark or stained. It depends on the species too. Many new canoes from Maine builders who use white cedar ribs and planking are very light colored. Red cedar planking will obviously be darker.

I just varnished an old canoe yesterday. I sealed it with 2 coats of an amber/garnet shellac and used very little varnish, so the shellac obviously keeps the varnish from penetrating. I am left with the warm, amber varnished interior. I don't think you can come close to a "clear" varnish on a new white cedar canoe, if that makes any sense.

 

[Andre Cloutier]

Dark is nice....

 

[chris pearson]

Did you really need to bleach it? I try to stay away from bleaching, that could be your problem. I love Z Spar Captains varnish too, never have had a problem.

 

[Howie]

Let's see...

Chris: I thinking that bleaching evens the color out as well as lightens it. The wood looks gorgeous after breaching. Really. It'd be the way to go... if I cold refinish in a way that didn't get way dark on me.

Fitz: I'm guessing that you've used shellac before without the problems I had with subsequent varnish layers not adhering. Did you do any special surface prep to the shellac layer prior to varnishing? And isn't there a problem when shellac comes in contact with water? I know alcohol dissolves it... but isn't water bad for it too?

Ok... Here's some pics.
Pic 1: After stripping

Pic 2: After cleaning:

Pic 3: An hour later after bleaching (still haven't got the stain right on the new ribs yet).

Pic 4: And now after 2 coats varnish. I had to put the white paper pad in the pic to get the color to be close to true life - it's with the lights in the garage. It truly is a bit darker that it appears here.

 

[H.E. Pennypacker]

Hi Howie -

First, as you've seen when stripping, cleaning, etc., wood generally darkens with wetting, no matter what it's wetted with, including varnish. Beyond that, the color and darkness of old wood varies tremendously depending on wood species and how the wood was treated over its lifetime. All of this has to do with the physics of light interacting with the material (wood, water, varnish, whatever), but that's beyond the scope of this discussion. You simply want wood that's not so dark, and presumably you want wood that's more even in appearance.

The more "open" the wood, the more light "gets lost" in the wood (wood appears darker) rather than being reflected (wood appears lighter). So if the canoe was left exposed to the elements without finish for years, there's not a lot you can do to fix the damage that causes it to appear dark when finished. However, there are some things you can do. First, use a really good cleaner/bleach. Te-Ka and Snappy are MUCH better than the cheap varieties on hardware store shelves. You might also do more than one round of cleaning/bleaching. Then you might also do a treatment with oxalic acid, which will further lighten and even out the tones of the wood. Following all of that, sand well and to a fairly fine grit to get a very smooth surface. The wood is still going to darken when finish is added, but as you build coats the tones will even out more, and the more build, the better it will look.

Looks like you've replaced some planking. If you still have some of the old planking, try some of these things to convince yourself that different treatments will produce very different outcomes.

Hope this is useful.

 

[Howie]

Thank you Pennypacker - that's a great explanation! I guess I knew everything you say, but having someone re-say it in such a logical way helps a lot. And what you say about how the wood has been handled makes a lot of sense. I've refinished canoes from the 20's that look lighter than canoes from the 60's.

So... I guess the upshot of all this is that it ain't my fault that it turned dark. Perhaps the wood would have turned out lighter if I chose to refinish using a technique that didn't cause the medium (varnish or shellac) to seep into the wood.

 

[H.E. Pennypacker]

You're very kind, Howie.

About finish seeping into the wood - that's exactly what you want to happen in order to get a good bond. When finishing, even new wood, there's a balance between getting the wood smooth to enhance its beauty and keeping it rough for adherence of the finish. Woodworking magazines and forums are full of questions and answers after people have sanded to very high grit, leaving the surface so polished that the finish won't adhere well. The reason we thin our initial coats of varnish is to enhance penetration, which in turn enhances adhesion. So the trick is to clean and treat the wood to remove old finish, dirt, stains, etc., and then sand carefully and thoroughly level the surface as much as possible (without polishing... I go up only through 220 on red and white cedar). Then apply thinned varnish to get good penetration and adhesion. Unfortunately, some canoes are simply going to be darker (or lighter) than some people might prefer. Personally, I love the variety among old wooden boats. I've seen some dark wood that's been well varnished and is spectacular.

H.E.

 

[MGC]

The wood will take on whatever color that it does...not too much can be done to change that.
For my taste I make an effort to try to blend the new wood (ribs, planking) so that it does not stand out too dramatically.
I also tend towards a low gloss varnish as a final coat on darker wood...that seems to make it look less "jarring".
I think satin finishes look better than super high gloss on old wood.

 

[Fitz]

Hi Howie:

Wow, you weren't kidding when you said, "dark". I can't offer much more. What maker/brand of canoe?

I scuff all the coats of shellac and varnish with 220 grit, thinking a little tooth is a good thing for adhesion. Like H.E., I don't go any finer than that.

I have had the occasional bubble in the finish that I blame on surface contamination, or possibly wax in the shellac. I am trying dewaxed shellac now.

I forgot to mention, the varnish coats protect the shellac against water. I have had no issues with water.

 

[Howie]

Fitz: It's a Penn Yan Hunter - 15'. Had a bit of a hard life: It was hung sideways from an inwale for some time, resulting in 5 broken ribs at the center plus a slight kink to the inwale at the center thwart. Then instead of tacks some bozo used a nail gun to tie the wood together to the ribs! The nails were stainless, thin, with no gripping rings, blunt with no head per se, and 3/4" long!!!!!. The blunt tips caused the wood to splinter, and they stuck out 1/4". Since they were stainless he hadn't a prayer of clinching the nails, but since there was no head to speak of the lack of clinching didn't really matter because the nails could be pulled out by the tail anyway - they had no gripping power at all! Plus parts of the insides, thwarts, & seats were 'varnished' at some point with what I assume was an epoxy mix because Dad's stripper wouldn't hardly touch it.

Ah well - it survived. The mahogany gunnels, seats & decks will look great on it.

Paddlephile: Matte? Really? Not me - the glossier the better. Think I'll paint it the Epifanes Yacht Enamel 'Deep Red' #3123. And yes, I stain the new wood too. Tough to match though when the color changes so much.

Again, thanks for comments all. Next in line is another Penn Yan - a 16' Rainbow. With 16 broken ribs! O joy.

 

[yankee2]

I have never built or restored a canoe, yet (so keep that in mind), but I think I may have the answer. I understand that all the old canoe makers laid down a couple of coats of shellac, in alcohol, as a sealer and primer, which prevents the varnish from being absorbed by the wood. Shellac is a solid in solution, and the alcohol medium dries rapidly, so there's really nothing to sink in. It is used that way on pine, to prevent the subsequent finish from absorbing in a blotchy manner. Finishing is a tricky and mysterious art, but I bet a couple of coats of shellac under the varnish would solve the problem.

 

[yankee2]

Howie, I made this suggestion independently, before I saw your post. I think shellac is the answer.

 

[Howie]

I don't know... Not sure I agree. I'm thinking Pennypacker has it right: oils found naturally in wood can dissipate over time; leaving voids for urethane/varnish/shellac to seep into. The deeper it sinks the deeper the wood tone will be. With both shellac & urethane we have solids dissolved in some medium, and with both the solids are carried as deep into the wood as the pores allow where in time the liquids dissipate and the solids remain. So would shellac solids look any lighter than urethane solids? I doubt it - I suspect even the clearest shellac is a deeper amber color than the Urethane I used.

Someone suggested I try an experiment with the ribs I removed. I'll try & do so soon!

And I'm thinking the old timers used shellac simply because it dried faster which afforded them faster turn-around time.

Thanks again - this is fun.