Boat Design Forums  |  Boat Design Directory  |  Boat Design Gallery  |  Boat Design Book Store  |  Thanks to Our Site Sponsors

Go Back   Boat Design Forums > Construction > Materials
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read Most Recent Posts Gallery Images Search

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 09-07-2010, 08:14 PM
captdan captdan is offline
 
Join Date: Sep 2010
Rep: 10 Posts: 4
Location: Key Largo
Teak Veneer Restoration

I am attempting to restore the interior on our 45' Hatteras. The teak veneer plywood around the salon windows has begun to weather due to leaks in the salon windows. After the window repair we need to tackle water stains. I imagine the orignal veneer was coated in teak oil, but we would like to update it to brightwork using epoxy/varnish. Would I be correct in assuming this method will not work on previously oiled teak or has anyone been able to accomplish this conversion?
Reply With Quote


  #2  
Old 09-07-2010, 08:29 PM
mydauphin mydauphin is offline
Senior Member
 
Join Date: Apr 2007
Rep: 575 Posts: 1,929
Location: Florida
Quote:
Originally Posted by captdan View Post
I am attempting to restore the interior on our 45' Hatteras. The teak veneer plywood around the salon windows has begun to weather due to leaks in the salon windows. After the window repair we need to tackle water stains. I imagine the orignal veneer was coated in teak oil, but we would like to update it to brightwork using epoxy/varnish. Would I be correct in assuming this method will not work on previously oiled teak or has anyone been able to accomplish this conversion?
Probably not unless you wash and dry teak with something that would remove oil. But you mention water stains. There are ways to bleach or tint wood to a more even color. Show us some pictures. Might be easier to put new teak veneer over area.
Reply With Quote
  #3  
Old 09-07-2010, 09:05 PM
PAR's Avatar
PAR PAR is offline
Yacht Designer/Builder
 
Join Date: Nov 2003
Rep: 3725 Posts: 14,511
Location: Eustis, FL
Yes, you can epoxy over previously oiled wood. The key is not to have a bunch of oil on the surface. With teak, and it's naturally oily nature, you need additional steps to avoid bond issues with epoxy.

The first thing I would do is remove the veneer if possible. Epoxy under varnish serves only one purpose, a waterproofing agent. To truly do the job right this means encapsulation, which requires the piece be completely "entombed" in epoxy, all sides, especially the end grain. If you're not going to do this, then you can skip the epoxy.

If you do epoxy coat, clean the wood, then scrape (preferred) or sand (with the grain) to provide "tooth". If you have stains, oxalic acid is a good choice to remove them. Once the piece is ready for epoxy, use a mixture of 33% isopropyl alcohol, 33% xylene, 33% acetone and scrub the surface with this combination of solvents (it's a personal secret formula for teak/epoxy bonds). Let this dry, which will not take very long as these chemicals have a quick flash off. Apply unthickened epoxy as soon as the teak is dry. If you're not comfortable with mixing these chemicals, use just straight acetone, though this isn't as effective as the special PAR mixture above, it does work and would be just fine on an interior trim piece.

It takes three coats to insure waterproofing and more will not hurt, though the film thickness may begin to causes issues. To save sanding, apply subsequent coats just after the previous coat has lost it's tack.

Once the epoxy is cured, you can sand and prep for varnish (or polyurethane) as desired.

If you're not epoxying, then I'd recommend a good quality polyurethane instead of epoxy. They are harder and more water resistant then varnishes. There are two types of polyurethanes, single part and two part. The two part polyurethanes are hands down the best stuff going, hard very durable, long lasting, high gloss retention and the most moisture resistant. Naturally, these also cost the most and are the more difficult to apply.
Reply With Quote
  #4  
Old 09-07-2010, 09:32 PM
mydauphin mydauphin is offline
Senior Member
 
Join Date: Apr 2007
Rep: 575 Posts: 1,929
Location: Florida
Par comments are great. He did mention you have to do all sides. If you don't moisture will get in and screw everything up.
Reply With Quote
  #5  
Old 09-07-2010, 09:36 PM
Petros Petros is offline
Senior Member
 
Join Date: Oct 2007
Rep: 1478 Posts: 2,543
Location: Arlington, WA-USA
You can varnish over an oiled finish, even oil finish should harden when exposed to air. Teak is a wood with a lot of oil in it already and is supposed to be used unfinished, and allowed to age, only requiring regular scrubbing. That means it will eventually turn gray if exposed to the sun as on a deck. If, as it sounds, it was used for intiror finish, it may have been oiled with a Tung oil finish. Any oil based finish or varnish can be applied over it, and it will bond well if you prep the surface and so as long as it is not peeling off.

Do not use epoxy on a wood surface, it is too hard and brittle, it will crack, allow moisture intrusion, darken the wood and peel off faster than a good oil finish. Epoxy is also toxic, and it will yellow and weaken with exposure to sunlight. Exterior varnish will hold up better on surfaces exposed to sunlight.

Sometimes you get water condensing around the windows from the cold metal frame, not from an actual leak, so verify you actually have leak before you remove all the windows. If you have water stains or mold (as opposed to just sun bleaching) than you might want to use a wood bleach first, the best is Te-Ka A&B Wood Cleaner from Travaco Products Div of ITW Philadelphia Resins (www.marinetex.com). Or you might consider a product called Teak Wonder from T-Jett Marine (of Miami, Florida). Daly's A & B Bleach is also good. (www.dailyspaint.com)

If the old finish is still well bonded over most of the surface you only need to scrap off the blistered or flaky stuff and than bleach the wood. After thee wood is dry, sand with 120 than 220 grit, clean off dust and apply fresh stain to match, or oil finish to the areas affected, first coat thinned 25 percent, and than apply several more coats 4 hours apart without sanding. And than build up several coats at full stength a day apart, sanding beween each coat to fair the patch. Than sand the whole part with 320 grit and apply a full coat of oil or varnish to the whole part.

If you need to strip the whole part because the finish can not be salvaved (too many cracks and penetrations or peeling), strip with Citristrip Paint and Vanish Stripping Gel (www.citirstrip.com). I think this is avaiable from big box stores like Home Depot. Sanding is a last resort to removing an old finish.

Varnish will hold up better than an oil finish, but for interior surfaces you can use an oil finish, Daly's Seafin Teak oil, made from tung oil, is good and it is compatible with most finishes. You can also use this product to wet sand before you varnish it. Do not use for an oil finish for exterior surfaces since it will not hold up to sunlight as well as an exterior varnish.

Best varnish would be Interlux #96, Epifanes, Mcloskey's Bote-Kote, or Man O'War. There are others too, most cost more and are not necessarily any better.

Good luck.
Reply With Quote
  #6  
Old 09-07-2010, 11:20 PM
PAR's Avatar
PAR PAR is offline
Yacht Designer/Builder
 
Join Date: Nov 2003
Rep: 3725 Posts: 14,511
Location: Eustis, FL
Quote:
Do not use epoxy on a wood surface, it is too hard and brittle, it will crack, allow moisture intrusion, darken the wood and peel off faster than a good oil finish.
I'm not sure of your experience or expertise Petros, but this is clearly incorrect by any stretch of the imagination. Okay maybe you like oil finishes, but they don't hold a candle to epoxy, in any way you'd like to measure them, so I have to question your logic, particularly in light of all the taped seam boats out there in the world.

Quote:
Teak is a wood with a lot of oil in it already and is supposed to be used unfinished, and allowed to age, only requiring regular scrubbing
Again, I'm not sure about your experience, but varnished teak is not only common but beautiful. Teak decks are supposed to be permitted to age, they are intended to be maintained, with regular cleanings (not scrubbings) and oilings which keeps it from turning gray.
Reply With Quote
  #7  
Old 09-08-2010, 12:06 AM
Petros Petros is offline
Senior Member
 
Join Date: Oct 2007
Rep: 1478 Posts: 2,543
Location: Arlington, WA-USA
Par,

This is not just my opinion but also in marine finishing guides as well. Epoxy paint on plain wood is not a good idea, it will yellow and crack, I know from personnel experience, and it is difficult to strip off later. I am talking about epoxy paint on wood without fiberglass. Taped seam boats have fiberglass cloth integral to the joint, as well as stitch n glue and strip built hulls, so the fiberglass supports the epoxy (the wood is just a core in that case). And even on those you have to put several coats of exterior varnish over it to protect it from the sunlight. If it is not a structural member, there is no reason to use epoxy on it. Epoxy is a structural adhesive that is costly and toxic, and does nothing to protect the wood, so why use it if it is not needed for the structure? It is just an extra costly step.

And yes, I was referring to teak decks that do not get a finish. Though I also love the appearance of finished wood, decks are meant to be practial. Interior panels are primarily for appearance, and having them finished is much preferred.
Reply With Quote
  #8  
Old 09-08-2010, 11:53 AM
apex1
Guest
 
Posts: n/a
Quote:
Originally Posted by Petros View Post
Par,
Quote:
This is not just my opinion but also in marine finishing guides as well.
That means just both are wrong!

Quote:
Epoxy on plain wood is not a good idea, it will yellow and crack,
It is by far the best idea to prevent water ingress, and the only idea we have in wood epoxy boatbuilding! Though in case of touching up a old veneer probably not the first choice.

Quote:
If it is not a structural member, there is no reason to use epoxy on it. Epoxy is a structural adhesive that is costly and toxic, and does nothing to protect the wood, so why use it if it is not needed for the structure? It is just an extra costly step.

Wrong in every point! Epoxy will provide the best protection on wooden structures even when it is not structurally required. It is absolutely inert once cured and not toxic. Only during shelf life one has to avoid skin contact.

Quote:
Interior panels are primarily for appearance, and having them finished is much preferred.
As PAR already mentioned, there is quite a lack of understanding the properties of these materials in your comments.

Regards
Richard
Reply With Quote
  #9  
Old 09-08-2010, 12:42 PM
PAR's Avatar
PAR PAR is offline
Yacht Designer/Builder
 
Join Date: Nov 2003
Rep: 3725 Posts: 14,511
Location: Eustis, FL
Quote:
Epoxy paint on plain wood is not a good idea
Agreed, I dislike epoxy paint, though epoxy primer I do like. Your original post didn't say epoxy paint, it said epoxy, which one could only assume meant straight epoxy. In that regard, my previous comments stand valid and the whole of the industry stands behind it.

Quote:
Epoxy is a structural adhesive that is costly and toxic,
Yep, I try to avoid the urge to eat it and smear it in my eyes, but sometimes I'm over come and can't help myself. It's especially good on toast.

Epoxy is also a coating and used as such world wide. Not only on wood, where there is literally no other product that can compete in waterproofing it, but on metals, concrete and a host of other materials. The taped seam boats you mention do not have 'glass sheathings on every surface, so I guess they're just wasting it on un-sheathed areas?

Quote:
you have to put several coats of exterior varnish over it to protect it from the sunlight
Well, darn you got me there, but you have to do this to wood anyway, if you expect it to have a pretty gloss and glow, exposed to UV.

Quote:
And yes, I was referring to teak decks that do not get a finish
Anyone that lets their decks go silver isn't protecting anything, especially their investment. Of course they get a finish, typically oil, though some made made products are showing some promise. A well kept and properly maintained teak deck isn't gray, it's a pretty yellow. Anyone paid to maintain a deck and permits it to go gray should be fired for not doing their job. It's not hard, though it does require considerable effort down here in sunny Florida with regular cleanings and oilings every other month.

It's thinking as you've displayed it, that caused me to join this forum nearly a decade ago, to dispel these myths, wives tails and old school rumors that have absolutely no bearing in reality. I've spent my whole adult life upgrading my opinions and thoughts about materials, techniques and methods as they evolve with recent advances and timed testing. No sooner do I get comfortable about a particular product, technique, method, etc. then I get a wake up call from a decade long study that's finally completed showing that I was wrong. An open mind and the willingness to continue the education about these natural and forced material, technique, etc. evolutions is the only way anyone can keep up and stay "in the groove" in regard to offering help or asking for money in services.
Reply With Quote
  #10  
Old 09-08-2010, 05:44 PM
Petros Petros is offline
Senior Member
 
Join Date: Oct 2007
Rep: 1478 Posts: 2,543
Location: Arlington, WA-USA
okay, fine you guys, pick your poison and use epoxy all you want. I used to think that way until I had some bad experiences with epoxy, and did some reading on finishes. So I "evolved" away from thinking epoxy is the best thing to use on wood. I now avoid it for most applications unless it is really necessary. This I say as an engineer with 30 years professional experience and someone who has been building wood boats since I was 11 years old.

One of the best known modern authors on the subject, Rebecca Wittman , author of "Brightwork: the art of finishing wood", will not use epoxy finishes on wood. She acknowledges there are many believers in epoxy sealers, but she is not one of them. She does use it for filling voids and gaps (mixed with wood flour), but not as a finish.

And it is wrong to say epoxy is inert, it is far from inert. It is an unnatural mixture of cross linked polymer chains, the bonds are chemically unstable over long term and break down, sunlight causes it to break down even faster. With time the compounds will go back to their constituent elements, breaking down, weakening, and turning back into dust. This is true of varnish as well, but exterior oil based varnish will last longer than epoxy when exposed to sunlight. So why use it if it is not in a structural application?

Many years ago the Boeing company "discovered" epoxy as a structural adhesive. Some of the "true believers" said it would make traditional fasteners obsolete, they were going to build whole aircraft with out rivets and bolts. They designed some fuselage sections that where the skins were joined with epoxy over lapping seams, one old time engineer insisted on having a few rows of fasteners until the technology was proven (rather than the 4 or 5 rows they usually employ on lap joints). Good thing they did, several years later all the epoxy joints were failing and if not for the fasteners the airplanes would have been coming apart at the seams. I worked there and our department wrote FAA approved procedures for replacing the epoxy joints and installing additional rows of conventional fasteners on the whole fleet of aircraft that used epoxy bonding.

Use epoxy and expose yours self to some of the most toxic materials you will find in a boat building, and much of it will not hold up as well as conventional methods and materials. So again I ask why use it?

Use it if you want. I see no need for it in this application.
Reply With Quote
  #11  
Old 09-08-2010, 06:40 PM
apex1
Guest
 
Posts: n/a
Quote:
Originally Posted by Petros View Post
Quote:
And it is wrong to say epoxy is inert, it is far from inert. It is an unnatural mixture of cross linked polymer chains, the bonds are chemically unstable over long term and break down, sunlight causes it to break down even faster. With time the compounds will go back to their constituent elements, breaking down, weakening, and turning back into dust. This is true of varnish as well, but exterior oil based varnish will last longer than epoxy when exposed to sunlight. So why use it if it is not in a structural application?

Sorry mate, that is nothing but bare nonsense! Cured Epoxy IS inert! At least the tastes a amateur can easily buy. Of course it has to be UV protected, no doubt.

Quote:

Use epoxy and expose yours self to some of the most toxic materials you will find in a boat building, and much of it will not hold up as well as conventional methods and materials. So again I ask why use it?

Use it if you want. I see no need for it in this application.
None of us said it is the best or only solution to be applied in this special case. Nobody was referring to Epoxy finish either!
You cheat! The edited post from saying "Epoxy" to "Epoxy paint" wasnīt correct too.

But after 35 years of wood epoxy boat building I can ensure you, it is by far the best stuff to avoid water ingress in wooden structures. And none of my boats turned to dust by so far!

And dead sure it is inert!

Your aircraft example was completely besides topic, due to the fact, that the metal glue used in that application has not much in common with the stuff commonly used in boatbuilding, except being a epoxy base.

Regards
Richard
Reply With Quote
  #12  
Old 09-08-2010, 07:21 PM
PAR's Avatar
PAR PAR is offline
Yacht Designer/Builder
 
Join Date: Nov 2003
Rep: 3725 Posts: 14,511
Location: Eustis, FL
I'm not going to bother Richard, this person is clearly not up to speed. In fact the electrical leads used on "in body (humans) electronics" are sealed with epoxy, especially because of it's inert nature, but hay, what do I know, I'm a two times over engineer with over 30 years experience too.

Aircraft are being built without rivets any more (for a few decades now) and they are using epoxy as the adhesive, cyanoacrylates also have made a huge impact as have polyurethanes, but what do we know. According to you, we are all still in the 70's. Rebbecca doesn't use epoxy because of the additional effort in repairs, which in her line of work isn't necessary, she just wants it to be shinny without runs.

The jury has been long in on all these myths and rumors, which were rampant in the 80's and early 90's, but now are well accepted by all, but the few that haven't kept up. Some just huddle in corner and hope it'll go away, so they can justify going back to their old methods.

In defense of Petros, I used to use penetrating epoxy like crazy and now very rarely. But again this is an example of permitting my opinions of things to evolve as the tests and jury come in on them.
Reply With Quote
  #13  
Old 09-08-2010, 07:38 PM
apex1
Guest
 
Posts: n/a
Paul,

this part should be edited:

>>>>>According to you,<<<<<

it looks like you address me.

Richard
Reply With Quote
  #14  
Old 09-08-2010, 08:40 PM
Petros Petros is offline
Senior Member
 
Join Date: Oct 2007
Rep: 1478 Posts: 2,543
Location: Arlington, WA-USA
okay fine, I cheat. If you mean inert by saying it is not chemically reactive, sure I agree, but the context was how durable it is as a finish. who is cheating now? Perhaps it is chemcially inert, but it is not chemically stable. different issue and this is what is relavant to a finish.

It sure would be nice if there was some kind of finish you can apply to wood, once. Unfortunately sunlight breaks most materials down, some faster than others, but most substances decompose with exposure to sunlight.
Reply With Quote


  #15  
Old 09-08-2010, 09:09 PM
apex1
Guest
 
Posts: n/a
Quote:
Originally Posted by Petros View Post
okay fine, I cheat. If you mean inert by saying it is not chemically reactive, sure I agree, but the context was how durable it is as a finish. who is cheating now? Perhaps it is chemcially inert, but it is not chemically stable. different issue and this is what is relavant to a finish.

It sure would be nice if there was some kind of finish you can apply to wood, once. Unfortunately sunlight breaks most materials down, some faster than others, but most substances decompose with exposure to sunlight.
No no Mate,

inert is inert, a clear and unmistakable term in science! Durable? Well, it is the most durable material in boatbuilding by so far! Of course it has to be processed and applied proper, that includes UV protection.
Chemically not stable? What a nonsense, it is absolutely stable and resists more environmental influence than any other boatbuilding material.

Again, donīt cheat please. Nobody recommended Ep as a finish!
Our recommendation was to encapsulate wood in Ep, not to misuse it as a varnish, which it is not. And even that recommendation was made conditionally. It was clearly said that there are other methods to address this restoration task.

This was a real hammer:

Quote:
Do not use epoxy on a wood surface, it is too hard and brittle, it will crack, allow moisture intrusion, darken the wood and peel off faster than a good oil finish.
when have you ever used Epoxy on wood Petros?
Reply With Quote
Reply



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Replacing Bulkheads: Veneer or not to Veneer... Mike2444 Boatbuilding 15 12-03-2009 05:24 PM
Teak and Beech veneer ply Gypsie Materials 0 03-05-2008 07:08 PM
Veneer - core foam - veneer hull sieagel Wooden Boat Building and Restoration 1 01-21-2007 12:39 PM
Veneer adhesive jbassion Fiberglass and Composite Boat Building 7 12-19-2006 07:06 AM
veneer racing shell restoration Kiwi100 Wooden Boat Building and Restoration 7 08-01-2005 06:31 PM


All times are GMT -4. The time now is 03:41 PM.


Powered by: vBulletin Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Web Site Design and Content Copyright ©1999 - 2014 Boat Design Net