WB 169 - Using Wood Bleach article

[Songololo]

Does anyone know what this article is like? Recommendable? I need to read up about using wood bleach for refurbishing a mast, the one in this thread (http://forum.woodenboat.com/showthread.php?t=114690).

Lance

[KAIROS]

I tried a couple of different concoctions found on the shelf in stores, and quickly decided they were by definition really unfriendly to wood. Decided to do a bit more sanding (which reduces mast diameter...I know) and live with the stains that remained. Somewhere here I read to not worry about anything higher than about 9' from deck......rarely scrutinized up there. So much of these cosmetic issues we fret about when restoring just seem to not matter later when sailing....and others care even less. Knowing it's good and maintainable is the thing. [could not find that WB issue]

[TimH]

I used Oxalic acid on my well weathered teak before sanding. Between the two it came out real nice.

Just be sure you neutralize it afterward though. A long time ago I applied varnish to oak after bleaching and not neutralizing well enough. The varnish came off real soon.

West marine has Oxalic acid for cheap. The pharmacy has it or 10X as much.

[KAIROS]

For TimH, the teak may have made the difference in the outcome. The same acid did a number on the pulpy parts (early-wood) of my spruce mast where I tested it. Nothing that some sanding would not fix, but it did wreck some of the wood.

[Lew Barrett]

It's important when using oxalic acid not to sand first. Bleach first. It will raise the grain, so prior sanding is at best a waste of time. I have not had trouble on good wood, although I can't recall if I have ever used it on spruce. Probably not.

I believe it is critical to bleach any teak (and most other woods as well) that have been previously varnished where the varnish has broken through. If you don't bleach the raw wood, it will turn black under the fresh varnish. I bleach even the smallest repairs. Blotchiness, which can sometimes be a fact of life with this sort of repair work, will usually disappear with exposure to sun. Some stains, especially when iron gets in the wood, are almost impossible to remove, and I find those the hardest to treat...often a waste of time.

Neutralizing is made considerably easier by not allowing any bleach to dry on the wood. The bleach should be rinsed off while it is still wet. If you want more bleaching time, keep slathering it on. Don't allow crystals to form on the wood. Bearing that in mind, bleaching is probably best done in shade.

[C. Ross]

The article in WB 169 is incredibly helpful. Explains the chemistry of stains, and why different types of bleaches work in different situations. I'll bet I've read it ten times.

If the hardware in your mast was iron or steel, those black stains will come out with oxalic (which is really cheap at the hardware or paint store). If not, then you may need a two-part bleach, which is entirely different chemistry. The article will tell you why, and how to use each. Good luck!

[David G]

Kairos,

A side note - I never would have thought of using oxalic acid on spruce. This species is so soft, that it's hard to imagine the setting where a little more abrasive wouldn't do the trick. Was it for discoloring from iron fasteners? Was the degradation from the oxalic acid generalized, or only at the discolored areas?

[KAIROS]

Kairos, A side note - I never would have thought of using oxalic acid on spruce. This species is so soft, that it's hard to imagine the setting where a little more abrasive wouldn't do the trick. Was it for discoloring from iron fasteners? Was the degradation generalized, or only at the discolored areas?

[this is not about the WB #168 article, but here you go]

The 33' mast had not been unstepped or maintained in about 10 years. Large areas of the mast had no finish left whatsoever. These areas, including the masthead, were sunbleached. The deep discoloration was mostly mold/mildew stains under remaining blotches of varnish. And, yes, after seeing the result of the acid on a small test area, I chose to just do some additional sanding instead of bleaching. The result was very good without acid, though I did sand quite a bit.

First photo shows the masthead as it came into the shop. Most parts of the mast were more deeply stained....this part had the benefit :D of no finish mostly, so was sunbleached.

http://www.yachtflyers.com/forum_images/mast_before.jpg

Second photo is after refinishing. We used Cetol Natural Teak (CNT) after a test on this portion of the spar. We compared the CNT finish against 2 clear varnishes and 3 other versions of Cetol....other versions of Cetol of course looked like mud.

http://www.yachtflyers.com/forum_images/mast_after.jpg

[John P Lebens]

I used a two part peroxide based wood-specific bleach that is neutral when it dries. On my mahogany, I wanted to even out some splotchy areas, but most important, I bleached to kill incipient fungus that could cause rot later. I even used a syringe to inject the bleach into stanchion screw holes to kill spores. Based on the amount of fizzing activity I got from the holes, it was the right thing to do.

It's too late now, but I wish I would have had read the article in WB before I dove in.

[Songololo]

I downloaded this article earlier today. It looks like a good summary of what various chemical options are available, when to use which method and how.

For those who don't know, back issues can be bought and downloaded electronically from the WBM store in PDF format.

Kairos - from the state of your mast, one would be tempted to not varnish at all, but just leave it bare. The dark patches beneath failed varnish seem in a worse state than the portion without varnish?

[KAIROS]

......The dark patches beneath failed varnish seem in a worse state than the portion without varnish?

This is so often the case with varnishes when the finish is breached.....they trap moisture and the wood gets stained. And, although varnished wood is a superior looking finish, this is why I chose to use the Cetol ('natural teak' version). It looks surprisingly close to a satin varnish finish.....but it is micro-porous: it breaths. And, it goes on so easy...you almost have to try to make it run and sag.

Some people who know what varnished wood looks like (wood boat owners), were surprised it was not varnish. As an experiment I have been using Epifanes on horizontal surfaces such as hatches, and this version of Cetol on vertical surfaces like cabin sides. I now wish I had gone with the Cetol Natural Teak alone. Looks very good and is so much easier to work with.

Leaving spruce unfinished is not an option. It at least must be oiled. Plus, my mast is solid but glued up in quarters, in section.

But this is not about bleaching. All I have to say on bleaching is to experiment with it on a small area first.

[Songololo]

Kairos - do you have a link to some product details ( or a link to a website) for this Cetol. I've just done a quick search locally for Cetol products by Sikkens and can't seem to find the one you are referring to. Once the bleaching and staining (if needed on the splines) is done I will need to move on to the varnish ... so ... your finishing comments are most welcome :)

[KAIROS]

Here (http://www.wholesalemarine.com/p/ILX-IVA-316Q/) it is in the USA. I didn't find it on the Sikkens international site.

I would definitely research it. On this forum the Cetol thread is old. The older Cetol products used iron oxide (rust) as the UV inhibitor, which made it a kind of muddy-orangish tint....not good if you like a varnish look. This Natural Teak was the first of their products to not use iron oxide. We tested it next to the other Cetols (iron oxide) and top notch varnishes. It looks very good (8/10) if we think of a perfect varnish job as a 10/10.

Do a test of your own on your wood. Strip off what you don't like. The main issue people had with the old muddy stuff was the appearance, not the protection provided by the finish. If the look of this new stuff is appealing, I'd go with it. Just borrow a small amount and try it.

Fly me over there. I'll bring a quart.

[Songololo]

Kairos - I found a local Sikkens dealer. They list the product as 'Cetol Marine Teak'. I'll be contacting them to see if I can get a sample.

How has this Cetol held up on your mast? I found a previous thread (2007') where you mentioned using it to finish the mast. Is it easily repairable? I have been considering Le Tonkinois (and possibly an Epifanes equivalent) up till now. I'm not too interested in an epoxy and polyurethane solution as seems to be used by some boat yards locally.

[David G]

I've been experimenting with Sikkens Cetol Marine for years now. The original (ugly fluorescent orange) I dismissed for aesthetic reasons. Then they came out with "Light" - which was a big improvement, looks-wise. Then, they came out with the new formula - in a now color... "Natural Teak" - and I decided to try it on a personal project.

I've now had it on a small, clip-on douglas fir leeboard... and the d. fir spars for a small balanced lug rig... for 2+ years. The leeboard is holding up fine. The mast is getting ground down, at the corner, by the yard rotating around the squarish mast. I don't fault the Cetol for this, rather the overall design. Shoulda been a round mast.

So... I've been quite happy with both the performance and looks of the Sikkens Cetol Marine "Natural Teak". The only complaint I've heard about the product which might well be legitimate is that it's hard to bring something back to bare wood once it's had Cetol on it. Also - you should know that you can't overcoat Cetol with most traditional spar varnishes. One apparently has to do a very thorough job of wooding before switching over to spar varnish - if that's a consideration for you.

[KAIROS]

.......How has this Cetol held up on your mast? I found a previous thread (2007') where you mentioned using it to finish the mast. Is it easily repairable? I have been considering Le Tonkinois (and possibly an Epifanes equivalent) up till now. I'm not too interested in an epoxy and polyurethane solution as seems to be used by some boat yards locally.

We are definitely into a sort of hot topic here. All I can tell you is my experience and opinion......If you lust after a perfect varnished wood finish, go with a varnished wood finish. If you want something easier to apply and maintain, which looks very good, go with the Cetol 'Teak'. When you do try it, if you want it removed, use 'Citris (http://www.citristrip.com/)Strip (http://www.citristrip.com/)'. Put that non-toxic stuff on and let it cook for 6 or 10 hours and the Cetol washes right off.

I have been applying varnish when required on various boats for about 35 years and have rarely ever been satisfied with the results. Varnishes are largely a real pain to work with. Plus, they do trap moisture once the finish is breached somewhere.....which is really bad for the wood. On the flip side, varnishes are very hard and durable. For a high wear-surface like a cabin sole, I use varnish with some translucent non-skid, for example. Cetol is softer and less able to handle wear and would not do well here.

But it is that relative 'softness' which allows it to be a bit pliable (wood moves!), easier to apply, and micro-porous. A notable problem area for varnishes are where there are wood joints at the corners of hatch frames, for example. Apply ten coats of varnish over clear bare wood there, and the finish will surely crack at the joints as the wood moves, water will get in and be trapped behind the varnish in that area, the wood will discolor and the finish will pop off. It's not much different than putting epoxy on real lumber and expecting it to survive wood movement. Varnish is very hard and relatively brittle.

Very easy to repair and maintain, easy to apply, looks very good....not quite as good as varnish. Try it. The photos are recent......

This photo shows the (hastily) Cetol-ed back of the cabin and (carefully) varnished main hatch and trim inside the companionway (Epifanes). All about 1960 honduras mahogany.....probably from the same tree. Huge difference in appearance? Other work is ongoing, hence fingerprints.

http://www.yachtflyers.com/forum_images/cetol_vs_epifanes.jpg

Here is the Cetol-ed mainmast (spruce) a couple of weeks ago. The sail luff tape is white.

http://www.yachtflyers.com/forum_images/mast_finish.jpg

Here's the Cetol-ed cabin side (honduras mahogany). The quarter round at deck/cabin joint is Cetol-ed teak and hence lighter. Raw teak deck. Bone white paint.

http://www.yachtflyers.com/forum_images/cabinside_cetol.jpg

[edit: and here is the Citris Strip taking off several layers of Cetol from hull topsides.....I think we put the striper on more than 12 hours earlier]

http://www.yachtflyers.com/forum_images/splines.jpg

That's all I have to say about Cetol Teak ;).