Glassing cedar wood fins - I cannot make the resin stick to the wood!

General Discussion
1

Hi there,

I’m having some issues with making glass stick to wood!

I’ve glassed over wood in the past with no issues but never cedar.

I’ve shaped a mini simmons and made my own fins out of cedar fence wood as suggested on surfersteve.

Attempt 1; I laminated 2 layers of 6oz onto one side of each fin, left the fins on our balcony, a few hours later it rained and the cloth seemed to have lifted off the fins. So I blamed it on the rain.

Attempt 2: I waited for the fins to dry out after pulling all of attempt 1s mess off, the cloth had gone quite rigid as you would expect, but not bonded to the fin and the resin between the cloth and fin was still very tacky. So fins dried and tidied up, I did the same again. Left the fins for 36 hours, then started to cut the glass around the edges of the fins only to realise that once more it hadn’t bonded.

Attempt 3; I thought I’d give up on laminating the fins and just coat them in resin, as suggested on surfersteve. Again, the resin has set, but a fraction of a mm above the surface of the wood.

So now I’m left with the issue of how to stick the fins to the board, if I can’t make resin stick to the fin!

I thought it could have something to do with the treatment applied to the wood for exterior use. The wood was orangey when I bought it, and after all my sanding and foiling it was a lovely whitey yellow colour, so I would have thought that most of the treated wood has gone. I’ve been using standard polyester resin that I’ve used before from Surfblanks in Sydney.

I’m sure it’s something very simple and would very much appreciate knowing what I’m doing wrong as it would seem a shame to buy some fins and put plugs in after all that sanding!

Thanks in advance.

George

2

Thanks Bondibarbie.  Yup, those are a couple minisimmons I did.  I used resin and cloth on both, but on the plys I left some overhang to insert fin rope around the edges.  I forgot about wiping down the cedar fins with acetone until I read someone else here mentioning it.  I did that too.  My buddy has been riding that board a lot for about a year.  So far, so good.

3

paint a thin layer of resin on the wood with your finger(enough so the wood absorbs it) then glass. 

don’t put anything on the wood after foiling…just paint resin on then glass

4

Ok, I’ll try that tonight. Thanks for the response.

I presume once you’ve got a thin layer on the wood you can laminate over that? Or apply a hotcoat straight onto the fins?

And just to be sure, do you mean just the resin or resin with catalyst?

Thanks agian,

George

5

The oil in the wood is rejecting the resin. You have to seal it with a thin layer of lam resin (with catalyst) like astevens suggests. Then laminate the fin with glass as usual.

~Brian

6

A old Hobie, (Terry Martin) trick for woods with a high tannin, and or moisture content is a thin coat of white glue.  It isn’t as dark as without but there is never any blister, separation, or bubbles.  If the wood is really dry, which yours isn’t there is never a problem.  I keep wood pieces for years sometimes before they go on a board, and sometimes the wait is worth the effort.

7

Thanks guys.

Will try the resin as there’s already a fair bit on them anyway.

8

Hey Bondibarbie,

I have nothing to add except to say I’ve used the cedar fence boards a couple times for keels.  Did what was mentioned above (thin layer of catalyzed lam resin on dry wood) and had no problems.  I decided I like the uniformity and the ease of shaping plywood instead though so I switched to that instead.  Something else I learned was how to add a resin halo around the fins.  Looks better and protects the fin too.

[img_assist|nid=1065137|title=cedar fins|desc=|link=none|align=left|width=640|height=427]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[img_assist|nid=1065138|title=Plywood fins|desc=|link=none|align=left|width=640|height=394]

 

9

Hi Wbrame,

Thanks for the confirmation.

Your keels look awesome, look like mini simmons tails too.

Did you just add resin to the fins in the top photo and resin and cloth to the bottom photo?

George

10

You mean western red ?....well its basically waterproof , which is why they use it for fences , house siding chamferboards and inside saunas !......try adding 5-10 % styrene monomer to your lam resin to thin it a bit.

11

A wooden boat builder here. I have been in the cedar battles before and can tell you it is coming from one of two things. Cedar is wet, cedar should be air dried for over a year before glueing. The second is oil, which makes cedar rot resistant. One trick I learned with the oil problem is to stick wood in denatured alchol and then let it bake in the sun for a couple of days. Cedar is actually the best wood for glueing if you are working with dried wood.

Since you said it is fence wood then it is wet, they do not dry fence wood. Next time buy from a lumber yard or cabinet making shop, they will tell you the moisture level of the wood before you buy. Worth the extra $ buying from the guys who will know about moisture levels.

Don’t worry happens to everyone, I saw a boat yard building 2 replicas of 1920’s boats and they used ash for the stringers and they twisted on them half way through construction because they did not check the moisture content. I had it happen to me with a cedar dinghy I was building for client (someone had moved drying lumber into the dry pile). A side note, make sure you are using epoxy because polyester is not a bonding agent, plus polyester is a killer.

Happy board building - The boards you guys are building are amazing, my first one is lumpy and not symmetrical…but soon it will be fine, I hope.

12

You might try acetone wiping and then 'priming' the fin twice with thinned catalyzed resin... up to 10% acetone with polyester.  Seal the primed wood with unthinned catalyzed resin before laminating with fiberglass.  If your wood isn't dry, forget it. 

Without priming/sealing you are likely going to get pin air under the glass even if the resin does stick.  Do not stick them out in the sun at any stage - you are definitely asking for outgassing/pin air as the wood heats up if you do this.  In the rain?  C'mon.

13

No I didn’t do it in the rain. I live in Australia, it’s summer here and it tends not to rain so much. I did it inside one evening, then moved the fins outside on a tray as there was no wind and a small roof over our balcony, the rain and wind came from no where and came in sideways. C’mon.

So we have people saying, no worries, the wood will be fine, just add a very thin layer to begin with.

People saying not to use polyester.

And people saying, no, do not use the wood at all!

It looks like a the thin layer of resin wiped on has worked for now.

Thanks for all the advice and opinions!

 

14

I don’t show here to be the devil’s advocate only to share

my experiences with the polyester~ wood composite experience.

 

 

 

First Polyester resin is the world’s worst glue. It only sticks to itself.

I’ve seen many many marine water craft be they surfboards or boats.

that have had a poly shell put over wood and the combination is a sure

failure unless it’s intended to stay indoors and see no marine exposure.

All it takes is one tiny break or crack in the poly surface and you can be

sure the wood will soon blacken and dry rot wil follow.

 

For starters you do want a good course surface to get you glue to bond.

I would leave the foil at 120 grit on the wood and then use a strong

solvent like lacquer thinner the wash the oils out of the wood. I think

it would take several washes to get the cedar to accept the glue

as it is very high in it’s own resin oils.

For glue IMHO epoxy is a far better choice. A single layer of glass and a polish coat

will serve the long term very well. The fin bead may be a little milky

but it can be quite strong with half the volume of a ploy bead.

Another added advantage of epoxy is that it is flexible and will not

shatter. Super Sap epoxy would be my choice. It cures quite slowly

but it does surface beautifully. Epoxy can be applied to Poly all you have

to do is tap off the area where you’ll set the fin and sand it to 60 grit.

The epoxy will hold just fine.

 

Worth considering IMHO.

 

Aloha, Rich

15

richs way best i m h o.

16

Probably just me, but grea to “see” you around Rich.

Plus - This is all pretty killer advice… Timely too, as I’m considering making some wood fins some day.

17

Yeah, third vote here regarding the inability of polyester resin to truly adhere to any type of wood for a decent amount of time.  That being said, cedar can be a bit tricky to glass because it is both very oily and porous.  

Tip 1 - you definitely need a cheater coat of epoxy on it before glassing.  Instead of trying to cure the resin quickly by puting it in the sun after applying the resin, try the opposite approach - heat up the raw foiled fin in the sun first, then apply the sealer coat of resin, then set indoors or a shady cooler spot.  You can stand there and watch the resin being sucked into wood.  This creates an excellent integral, mechanical bond to the wood. 

Tip 2 - once your cheater coat has dried, wash it with denatured alcohol or acetone.  The purpose of this is to remove any oils that may have migrated to the surface of the wood from the slight exotherm of the resin. No need to scuff the resin before glassing - most likely will expose the wood again and in one way or another create bubbles or dry weave.

 

Glass and cure in an ambient or slightly falling temperture. 

Yeah, and halcyon is not joking about the Super Sap. I started using it a couple months ago and it almost makes hand sanding and polishing a pleasure -excellent stuff! 

Orale!

18

yea and verily varlet!

EEEEEEEEEEPPPPPOOOOOXXXXIE!!!

rich halcyon says it on the square

you too can be a success

at this glass the wood problem.

Be all thet chew can be 

use that epoxy…

…ambrose…

 

off topic harry the hipster…

 

http://www.youtube.com/watch?v=Ql-1_uolBF4&feature=related

keep the beat move over jerry lee lewis

the professor is here for your 

refresher course.

19

Hello Wbrame ,

I'm in your town and I'm looking for someone to make me a set of plywood keel fins. With or without the halo. Hopefully birtch or maple ply.  At least one layer of cloth on each side. I have a template that I want but if you already have some made I'm flexable. Please contact me via PM or the Low Tech Lab thread or this Sway's link......

http://www2.swaylocks.com/forums/lets-make-deal-2011

 

Thanks........Stingray

20

so from what I understand you are saying that the best way to make it stick is to apply a layer of resin and catalyst to the bare wood before fiberglass cloth you want to let that dry before glassing over it, correct? not apply the layer of fiberglass cloth while the catalyzed resin is still wet? Would using spar varnish work the same? (waiting til it’s dry i assume) or would glass not stick to it