BYYB Forums

Hi everyone...after about 5 days off (visitors and sailing lesson) I finally got out and played with the epoxy yesterday and it lead to some questions...

1) "Paint both sides"?  In the Stevenson video they talk about painting both sides of a piece of wood when the parts will be under the water...BUT they are using plastic resin glue in the video...so I was wondering if this is true with epoxy...

2) Yesterday I added wood floor to the mix to test the consistency...for the KEEL glue up...which I would like to do today...is peanut butter the goal??

3) I am affraid to mix up too much at one time since I have been warned how much it can heat up in the container...so how much is too much...after I mix it I will be using it...so its not like it will sit there forever...

4) Wood Flour vs. silica....I have both...what times and purposes do i use each?

Thanks...

Matt

I used both silica and wood flour in mixes for gluing.  My idea was to have the wood flour for sanding and thickening and the silica for smoothness.  I put them in in a ratio of one part silica and 2 parts wood flour.  I didn't go to peanut butter thickness.  Most of the gluing I did wasabout whip cream consistency. 

For glue ups I would wet the surfaces with straight epoxy and let that start penatrating while I stirred in the wood flour and silica.  I spread the thickened mix on one surface then put the pieces together with a bit of sliding back and forth to make sure there was good contact.  I like the whip cream thickness because it was easier to smooth the glue and it ooxed out the seam of the glue up.  There were still times I would have to patch the glue line but usually I got a nice consistent glue line.

The time it takes for the goo to go thermal varies with the hardener you use, the temperature and the container you mix in.  I use slow hardenerm and small paper cereal bowls for most glue ups.  Sometimes I spread the mixture on a piece of scrap plywood, to thin it out, and use it like a painter does.

I am not an epoxy expert.  Building my boat was my first experience with anything but the 5 minute stuff you buy in the double syringes.  The method I used was gleaned form things I read on the forum and tried on smaller glue ups before doing the larger ones.

1 - I never watched the video myself but I would imagine that "both sides" means "both sides" regardless of what the coating is.  I'm not sure which parts other than the rudder would have "both sides" wet at the same time though.  Me - I coated and painted everything I could.

2 - Smooth peanut butter is about right.  You want the goop to stay put when you apply it, but to be liquid enough so that it will penetrate the wood.

3 - It depends on how fast you're applying it, how much surface area the container has, how hot it is outside, and how "fast" the hardener is that you are using.  Curing epoxy generates heat which in turns, causes it to cure.  A large puddle will take longer to cure than the same amount in a plastic cup.  An inch or two in the bottom of a coffee-cup sized container will probably be fine.  On a hot sunny day though, I've had resin cure almost as fast as I could mix it until I moved into the shade.

4 - Fillers thicken and add their own properties to the mix.  Wood flour helps colour match, is good for filling screw holes or making fillets and sands relatively well.  Silica add strength and will destroy your sander (so good masking and cleanup is a good idea so that you don't "have" to sand).  There are also a whole host of other commercial fillers out there with different properties.

Regarding glue:  I thicken with equal parts woodflour and silica.  The proportions aren't critical.  Thicken to the point resembling peanut butter.  In the summer, spread the glue on a small paper plate to achieve a large surface area, and use the slowest hardener you have.  Keep the rest in the refrigerator until you need it.  It will keep it from "going off" too soon.

Dave

thanks guys...bottom line...I NOW HAVE A KEEL...NOT THE PRETTIEST KEEL...it will take a lot of shaping once the epoxy is set...but I learned a lot about mixing...its now getting warm...but starting around 10am we were okay...

once the keel is shaped the next steps will be much faster since i have already cut out many of the parts...

thanks for the ideas...did not see dave's until now...but i read the first two responses before we started and they helped...

will add an update on my blog tonight...i hope...

matt

One mistake that I made on my keel was to "fair" one part lower than the other.  As you work on yours, use a long stick to make sure that the bottom will sit flat with no low or high spots.

Regarding "finishing both sides of the wood".   Just as in any woodworking project, If you only finish one side of the project the wood will warp and crack as the finished side becomes stable and protected, the unfinished side will absorb moisture and warp, crack and check as it is still unstable.

So...if you epoxy one side, epoxy coat the other.  Paint one surface, paint the opposite side as well.  Glass one side, glass the other, although in the case of plywood, glass and fair the lesser quality side "out to the weather", keep the higher quality side to the inside of the boat if it is not going to be glassed and painted.  You will have a better finished project as well as providing a higher quality finish to the lesser side of the plywood.  Both sides benefit and your project will last longer, finish out easier and be more stable and easier to maintain.

I know that this is counter intuitive, but think about it.  You fill, protect and stabilize the outside of the boat, you apply the best finish to the weather and maintain it to a higher standard.  Therefore, build with the best side of the plywood to the inside where you will likely not finish to the same degree as the outer surfaces.  Lesslong term issues with the lower graded side of the plywood as you are filling, fairing, epoxy coating, glassing, fairing, filling, etc and then applying a higher quality painted surface to the weather and wear.  Now the inside can by virture of the higher graded side in be less work to finish out and will have less issues with maintence in the long run.  

Thanks Barry...

I agree on maintaining and finishing the inside and outside of the boat...I think I meant something very different though...lol...

I did not mean paint or finish for the boat...I am faaaaar from that...I am in the first steps and my early question was much more "beginner-ish"...

In the 'how to" dvd for the stevenson weekender they "paint" or coat both sides when LAMINATING the keel parts...I was asking about that since they were  using plastic resin glue back when they made the video...and I am using epoxy for the first time...so with it being bettrer I was not sure if I needed to use or coat both sides of the wood as I laminated them...

What I ended up doing is "wetting" out BOTH sides of the wood with straight epoxy/hardener...and then mixing up another batch with wood flour and spreading that on one surface before I screwed the pieces together...

It worked well...I had squeeze out on the edges so I think there was enough glue...

Thanks everyone...

matt

Matt you want to paint the epoxy on both pieces of wood that you are going to glue as it will penetrate both sides evenly. Then apply the peanut butter (wood flour) ;D epoxy. Also remember, you will not need to apply the pressure necessary when using wood glue. Clamping too hard will squeeze out epoxy that should be left in the joint. ;D

thanks warren...I am pretty sure that's exactly what I did..."painted" clear epoxy on BOTH surfaces of the wood and then with it wet I went back and added the peanut butter onto one side and then screwed them together...

I did not clamp the wood at all...just put the screws around the edges...and some did squeeze out from the edges===i may have put too much...but I hope there is enough still between the pieces of wood...