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White oak and epoxy

Posted: Thu Nov 04, 2021 12:49 pm
by jbo_c
I was planning on making my barge runners out of white oak, but just stumbled on a discussion on another forum that it doesn't play well with epoxy. According to that discussion it doesn’t take epoxy well and epoxy glued joints with it are undependable.

Is there anything to that?

Do I need to re-evaluate my choice?

Thanks.

Jbo

Re: White oak and epoxy

Posted: Thu Nov 04, 2021 5:34 pm
by TomW1
jbo here is an article on oak and epoxy by West Systems that explains why not the twain shall meet: https://www.epoxyworks.com/index.php/ep ... ex%20Epoxy. They recommen Ash or if you can get it some good oldgrowth Southern Yellow Pineg from one one of your lumber yards down there.

Tom

Re: White oak and epoxy

Posted: Thu Nov 04, 2021 6:06 pm
by jonnymac
if you are coating the wood with epoxy, you don’t need a rot resistant wood anyway. White oak was used in ships where the wood was unprotected or like in war ships where the strength was needed.

I would use douglas fir as its as strong, but lighter than southern yellow pine. what ever you get, don’t get construction lumber, its kiln dried to a higher moisture content and lower temp and as a result the resins aren’t set. this can cause bonding problems, as well as when it dries it will change more dimensionally.

Re: White oak and epoxy

Posted: Thu Nov 04, 2021 6:55 pm
by fallguy1000
White oak runners would typically be bonded to the hull with 5200 so they can be cut off when the get bad. But he warned; it takes a good 7 days for the cure.

Re: White oak and epoxy

Posted: Thu Nov 04, 2021 10:16 pm
by jbo_c
Dang. I just thought it would be good because it’s hard. Wish I’d known bonding wasn’t good before I ordered.

Guess somebody will get a nice white oak something for Christmas. :)

Mill didn’t have ash or cypress. May just make the runners out of ply. Seems expensive, though.

Jbo

Re: White oak and epoxy

Posted: Thu Nov 04, 2021 10:36 pm
by fallguy1000
Just use the wo for the runners, but glue them on with 5200. Plywood will delam if you leave it in at all. It puffs on the edges. Even marine ply is not really made for full time immersion.

Re: White oak and epoxy

Posted: Fri Nov 05, 2021 11:07 am
by VT_Jeff
fallguy1000 wrote: Thu Nov 04, 2021 10:36 pm Just use the wo for the runners, but glue them on with 5200. Plywood will delam if you leave it in at all. It puffs on the edges. Even marine ply is not really made for full time immersion.
Agree with Dan here: use the oak, either with 5200 or with g-flex. Mark up the bonding surface considerably for a good mechanical bond.

Re: White oak and epoxy

Posted: Fri Nov 05, 2021 11:12 am
by fallguy1000
VT_Jeff wrote: Fri Nov 05, 2021 11:07 am
fallguy1000 wrote: Thu Nov 04, 2021 10:36 pm Just use the wo for the runners, but glue them on with 5200. Plywood will delam if you leave it in at all. It puffs on the edges. Even marine ply is not really made for full time immersion.
Agree with Dan here: use the oak, either with 5200 or with g-flex. Mark up the bonding surface considerably for a good mechanical bond.
Right! Use some 40 grit and scratch it real good..

Re: White oak and epoxy

Posted: Fri Nov 05, 2021 11:15 am
by Jaysen
maybe i'm lucky, but I've not had issues with epoxy on white oak. The key things I did
1. clean clean clean
2. don't sand too smooth (stop at 80)
3. build thin layers of neat before glue
4. glue with dowels/screws for alignment but leave them in. :)

That said, I've only epoxied a small strip on a sailboat and a pile of furniture. No issues yet.

If you use ply, be ready to maintain. It will expand at the end (marine wood from BBC has not delamed but it looks like it wants to).

also... my race boat specifies white oak epoxied several places. No one has reported any failures. They are in the first transat now.

Re: White oak and epoxy

Posted: Fri Nov 05, 2021 11:58 am
by fallguy1000
But why would you epoxy on a wear strip anyhow?

Re: White oak and epoxy

Posted: Fri Nov 05, 2021 12:01 pm
by Jaysen
fallguy1000 wrote: Fri Nov 05, 2021 11:58 am But why would you epoxy on a wear strip anyhow?
Because when you remove it, you don't have to deal with the silicone mess that 5200 leaves behind. Have you ever tried to really get 5200 off a spot that you need to paint or glue? Damn near impossible to get a clean surface after 5200 or 4200 in my experience. you just grind that silicone into the lower layers.

Re: White oak and epoxy

Posted: Fri Nov 05, 2021 1:53 pm
by jbo_c
I really thought I had read that Jacques recommended ply for strakes and runners. I must’ve dreamed that.

These runners will not see much wear. Yeah, they will occasionally hit something real, but this is a slow river boat so will see more sticks and sandy bottoms than anything else.

Jbo

Re: White oak and epoxy

Posted: Fri Nov 05, 2021 2:08 pm
by fallguy1000
Jaysen wrote: Fri Nov 05, 2021 12:01 pm
fallguy1000 wrote: Fri Nov 05, 2021 11:58 am But why would you epoxy on a wear strip anyhow?
Because when you remove it, you don't have to deal with the silicone mess that 5200 leaves behind. Have you ever tried to really get 5200 off a spot that you need to paint or glue? Damn near impossible to get a clean surface after 5200 or 4200 in my experience. you just grind that silicone into the lower layers.
My beaching keel timbers are on per designer with 5200.

Re: White oak and epoxy

Posted: Fri Nov 05, 2021 4:43 pm
by jbo_c
I found some ash, but it’s 50% more than the white oak. Good thing I didn’t get into this for the savings. :)

Jbo

Re: White oak and epoxy

Posted: Fri Nov 05, 2021 6:04 pm
by jonnymac
so are these going to be outside the hull, unpainted or painted?

white oak in freshwater continuously submerged is going last as long as the boat. so I wouldn’t worry as much about repair. if you use epoxy and it falls off, you just put another piece back on.

The white oak used to repair the uss constitution is kept in a pond. They take out what they need, then put the rest back.

Re: White oak and epoxy

Posted: Fri Nov 05, 2021 6:16 pm
by jbo_c
Strangely enough. I think I knew that about the Constitution.

These will be on the outside. They’ll be glassed and coated with epoxy/graphite.

Jbo

Re: White oak and epoxy

Posted: Sun Nov 14, 2021 1:11 pm
by Dan_Smullen
As a guy with a white oak clamping board, skeg and strakes, wish me luck!

Re: White oak and epoxy

Posted: Thu Dec 09, 2021 1:17 am
by joe2700
My rub rail is white oak that is epoxied to the hull and it took an large amount of force to clamp it on around the bend near the bow especially to force the twist so if you are epoxying well prepped white oak to somewhere not under a lot of strain I don't think you will have a problem. I even have an epoxied scarf that also survived the bending. I think I sanded with 80 grit, cleaned well with denatured alcohol, and glued with gel magic.


This is the post where I scarf and then install the rubrail: viewtopic.php?p=418950#p418950