Rot Prevention - Woodworking Talk - Woodworkers Forum
 
Thread Tools Display Modes
post #1 of 15 Old 07-09-2020, 05:50 AM Thread Starter
Senior Member
 
ducbsa's Avatar
 
Join Date: Jul 2014
Location: Virginia
Posts: 435
View ducbsa's Photo Album My Photos
Rot Prevention

When I made the bench in my avatar from white oak, I left it bare wood for the first couple of years. Then I used Epifanes spar varnish. It had already started to crack on the surface shown below, so I tried to brush extra varnish into the cracks. Recently I became aware of the extent of the rot, 1" deep over most of the length.

Was it bad luck with the lumber used or exposed end grain? Would a different design with veneer over the exposed end grain have saved it?
Attached Thumbnails
Click image for larger version

Name:	Plan a.jpg
Views:	22
Size:	386.3 KB
ID:	392073  

ducbsa is offline  
Sponsored Links
Advertisement
 
post #2 of 15 Old 07-09-2020, 08:04 AM
Senior Member
 
Join Date: Apr 2012
Posts: 3,024
View Quickstep's Photo Album My Photos
End grain exposed to rainwater creates an environment conducive to rot. The fresh water moisture supports the bacteria that cause rot. The other end of the leg is susceptible too. As it sits on the ground, water gets under it and doesn't dry, then gets wicked up into the end grain. White oak is fairly rot resistant, but it's not rot proof.
Quickstep is offline  
post #3 of 15 Old 07-09-2020, 08:55 AM
Senior Member
 
Join Date: Aug 2017
Posts: 2,842
View Tool Agnostic's Photo Album My Photos
In addition to the above helpful comment, I wonder if the climate where you live has something to do with the cracks. You live in Virginia. Do you see a lot of rain/freeze/rain/freeze cycles? That could open up the cracks over time.
Tool Agnostic is offline  
Sponsored Links
Advertisement
 
post #4 of 15 Old 07-10-2020, 11:44 AM
Senior Member
 
Join Date: May 2019
Posts: 103
View JohnGi's Photo Album My Photos
That's a very attractive bench and a sad story about it. perhaps some part of this may help.
I built 2 of these garden gates 15 years ago with red oak. I treated them with a wood preservative, zinc naphthenate. I was working with the stuff at the time. It was a bit of an experiment. They have held up extremely well. Even the wood in the corners most susceptible to moisture damage is still uniformly sound. There is no other finish on them. I live in a much colder climate. Also, they are porous red oak, not white oak, so they soaked up a lot of the stuff. I think Louisiana Pacific sells this in small applicators to treat the cut ends of their engineered wood siding. Cuprinol is a commercial preservative with similar chemistry, but I think it is copper rather than zinc based and can discolor the wood. If the wood will absorb it, working preservative into any cracks should help. These are toxins, not repellants. They kill what eats the wood after it takes a bite not before.

It's been my experience that gluing to end grain causes more problems than it solves. Any gap becomes a point of water entry, and then the glue line is a trap rather than a barrier. In architectural pieces, metal flashings are the common way to cover exposed end grain. I cut and folded thin aluminum to cover the exposed end grain at the tops of the 3 brackets that attach this small door canopy to the wall behind it. This is trickier on a piece of furniture, but I've seen copper bent and hammered to cover the tops of posts.

I subscribe to the old theory that knife finished end grain weathers better than sawn or sanded end grain. After I cut the white cedar fence posts to pyramid tops, I cleaned them up with a block plane; and they haven't fuzzed up since the fence was built. The curved ends of the brackets and rafter tails in the door canopy were finished on a shaper with a jig, and they remain as smooth and unchecked as the side grain. Not sure how you worked the curved ends on the bench posts.

Finally, preservationists generally use epoxy to stabilize deteriorated wood. Forest Products lab did a study that identified epoxy as the most effective long term moisture barrier on wood.

I hope you find a way to enjoy your beautiful bench for many more years.
Attached Thumbnails
Click image for larger version

Name:	garden gate a.jpg
Views:	18
Size:	328.8 KB
ID:	392151  

Click image for larger version

Name:	garden gate b.jpg
Views:	20
Size:	546.2 KB
ID:	392153  

Click image for larger version

Name:	back door canopy a.jpg
Views:	16
Size:	268.9 KB
ID:	392155  

JohnGi is offline  
post #5 of 15 Old 07-11-2020, 06:29 AM Thread Starter
Senior Member
 
ducbsa's Avatar
 
Join Date: Jul 2014
Location: Virginia
Posts: 435
View ducbsa's Photo Album My Photos
Those surfaces were cut with band saw and sanded. Copper flashing would have looked good. Forming that shape would have required quite a learning curve for me, but maybe with annealing it a lot, the copper would have been more workable than I anticipate. There were other issues that made me scrap it. I saved the masonite templates for the bandsawed pieces, so maybe a new one?
ducbsa is offline  
post #6 of 15 Old 07-11-2020, 01:16 PM
Senior Member
 
_Ogre's Avatar
 
Join Date: Feb 2013
Location: Motown
Posts: 688
View _Ogre's Photo Album My Photos
i believe your choice of oak is the downfall of your bench, that and going a couple years before sealing it
_Ogre is offline  
post #7 of 15 Old 07-12-2020, 05:02 AM Thread Starter
Senior Member
 
ducbsa's Avatar
 
Join Date: Jul 2014
Location: Virginia
Posts: 435
View ducbsa's Photo Album My Photos
A lot of references recommend white oak, so I thought it would be fine. The design has a lot of surfaces to revarnish every year or so and I was looking for low maintenance. What species and finish do you recommend?
ducbsa is offline  
post #8 of 15 Old 07-13-2020, 09:35 PM
Senior Member
 
Join Date: May 2019
Posts: 103
View JohnGi's Photo Album My Photos
Made out of 5/4 and 6/4 stock, I'm not sure you could do better than white oak. The weatherable commercial softwoods I can think of would not be strong enough for this design. There's the odd stuff: cypress, tamarack, black locust. All very durable, but with problems of availability.

Not finishing the bench may have been your downfall. This is the best advice I have ever been given on exterior finish: It is preventative maintenance. If you wait until it "looks like it needs it", you have waited too long. I worked with the American Wood Preservative Association "L" joint test for a while--a nasty test that deliberately cracks a paint finish to create a point of water intrusion at the corner joint, and I learned that keeping water out is by far your best bet. A lot of folks swear by Epifanes, but I've never used it. I think it helps to seal with water resistant glue the end grain in any joint. When water does get in the joint, it slows it seeping into the end grain. I used a lot of Weldwood plastic resin glue for this at one time and thought it worked well.
JohnGi is offline  
post #9 of 15 Old 07-13-2020, 11:09 PM
Senior Member
 
Join Date: Apr 2012
Posts: 3,024
View Quickstep's Photo Album My Photos
Quote:
Originally Posted by ducbsa View Post
A lot of references recommend white oak, so I thought it would be fine. The design has a lot of surfaces to revarnish every year or so and I was looking for low maintenance. What species and finish do you recommend?
I think white oak (not red) was a fine choice, but the Achilles heel was exactly the place where you showed the arrow pointing in your drawing. That's a lot of end grain facing skyward.

The best choice would be teak, but take a paramedic along when you get the price. IPE would be a good choice as well for weather resistance, but it's somewhat hard to machine.

Paint is the best finish, but if you want to see the wood, a high quality marine spar varnish like Epifanes would be the next best thing, but since it's clear, the sun will degrade the bond between the wood and the varnish will eventually peel. To protect the varnish make a cover out of Sunbrella Outdoor Fabric.
To protect the cover,,, (just kidding)
Quickstep is offline  
post #10 of 15 Old 07-14-2020, 06:06 AM Thread Starter
Senior Member
 
ducbsa's Avatar
 
Join Date: Jul 2014
Location: Virginia
Posts: 435
View ducbsa's Photo Album My Photos
The Weldwood can says Indoor Use, did you use it outdoors?

ducbsa is offline  
post #11 of 15 Old 07-14-2020, 09:48 AM
Senior Member
 
Join Date: Apr 2015
Location: NE FL
Posts: 616
View DrRobert's Photo Album My Photos
I would be looking into a penetrant that kills micro organisms, then seal with epoxy.

I’ve seen products to use in harden punky wood but I don’t know how well they hold up to elements.

Robert
DrRobert is offline  
post #12 of 15 Old 07-15-2020, 08:42 AM
Senior Member
 
Join Date: May 2019
Posts: 103
View JohnGi's Photo Album My Photos
Yes, that's the stuff. I would not use it for something that would be immersed in water like a cutting board or a boat hull, but it handles weather just fine. The Palladian window in the background is one of several circle head windows and one circle head exterior door that I built for my house in 1984 out of white pine. The curved head jambs and top rails have edge gluing done with plastic resin glue, and there is no sign of glue line failure in any of them.

I'm not sure why they say interior use only. I worked with catalyzed PVA in RF presses in millwork plants for non structural exterior use, and I thought the plastic resin glue that I used in my own shop held up just as well.
Attached Thumbnails
Click image for larger version

Name:	bedroom window a.jpg
Views:	6
Size:	113.9 KB
ID:	392445  

JohnGi is offline  
The Following User Says Thank You to JohnGi For This Useful Post:
ducbsa (07-16-2020)
post #13 of 15 Old 07-16-2020, 07:23 AM
Senior Member
 
Join Date: Apr 2012
Posts: 3,024
View Quickstep's Photo Album My Photos
Resorcinol glue and epoxy are also options for glue. Epoxy as a coating alone doesn't hold up well outdoors. It UV degrades from the sun and gets hazy. You can use epoxy as a sealer, but it has to be coated with a UV inhibiting varnish.

It would be ideal if you could re-engineer that front leg so it didn't have all the end grain exposed in the curve. I do think your idea of covering that end grain with copper would look cool. If you do that, you should hold it on with something like 3M 5200 to prevent water from getting under the copper and sitting there.
Quickstep is offline  
post #14 of 15 Old 07-16-2020, 08:13 AM
Senior Member
 
Join Date: Apr 2016
Location: Troy Michigan USA
Posts: 1,224
View gmercer_48083's Photo Album My Photos
I suspect it was not white oak. Most people can't tell the difference. If you still have a piece of the oak used... take a 3" (long grain) piece, and place it into a pan with 1/2" of alcohol with the wood grain standing upright. If it is red oak... after about 5 minutes the alcohol will wick up 3"... confirming red oak. White oak will not do this. That is why boat builders don't use red oak. Another way is to take a 3" piece and blow with your mouth on one end with the other end submerged in a glass of water.... if bubbles appear in the water it is red oak. White oak will not.

Gary

Woodworking is like wetting myself....Only I know that warm feeling!
gmercer_48083 is offline  
post #15 of 15 Old 07-17-2020, 07:02 AM Thread Starter
Senior Member
 
ducbsa's Avatar
 
Join Date: Jul 2014
Location: Virginia
Posts: 435
View ducbsa's Photo Album My Photos
My hardwood supplier said it was white oak and the other pieces held up well.
ducbsa is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Woodworking Talk - Woodworkers Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome