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Permalink Reply by Eric Loudenslager on April 17, 2011 at 5:41pm

What boat are you building?  Is it a frame design or stitch and glue?

 

If it is stitch and glue you will want to use biaxial fiberglass tape on the chine.  If it is a frame design you have a decision of whether to wrap the chine with glass or not.  See various previous discussions on glassing the bottom on frame boats.  

 

I built using stitch and glue.  The bottom is 5 oz kevlar, then 6 oz glass.  The chine is 6 inch 6 oz biaxial tape covered with 6 inch 6 oz glass tape, and then the 6 oz glass on the bottom was wrapped (draped) over both tapes about 4 inches down the side of the boat.  The order was - epoxy the bottom panel, let it cure; sand with 80 very lightly...just to remove the raised wood fibers; epoxy the 5 oz kevlar; 6 oz biaxial chine, 6 oz plain weave chine tape; 6 oz over the entire bottom.  Fill the weave with epoxy mixed with black graphite.  No paint on the bottom and edge of the side.

 

When I glass a plywood panel with epoxy I lay the cloth down on the panel, mix up about 150 grams of epoxy, pour it out in the middle of the cloth on the panel in a big S wave, use a plastic trowel or spreader to wet out the cloth.  Add epoxy as needed until the entire layup is wetted, work from the wet area into dry. Then squeegee off the excess.  You just want the cloth wet out.  You want to see the weave of the cloth and there should be no white areas where the cloth isn't wet out and there should be no shinny wet areas.  The shinny wet areas have to much resin.  The glass can float in the resin.  You want it in contact with the wood.

 

I epoxy coat the bare plywood before glassing to avoid starving the glass/wood lamination.  The wood will soak up epoxy.  It you don't add enough resin to a layup you wind up with a poor lamination between the glass and the wood.  Also, the wood will out-gas releasing bubbles that can get trapped under the glass.  If you put a thin layer of epoxy on the wood any out-gassing should completely escape without bubble formation.  I actually thin that first coat of epoxy - 25% with ethanol.  Manufacturer recommends using lacquer thinner to thin epoxy....but I tried ethanol and it cured so I used it.  My boat hasn't delaminated!

 

Interlux Brightsides does not need to be primed according to many.  I primed using the epoxy pre-kote.  In any case, you want to fair the side panels before painting otherwise when you sand between coats you are going to find you will sand through high spots.  The low spots will use too much paint to use as fill.

 

I painted the inside.  I left the fly deck, gunnels, and a few interior elements clear so it looks like a wood boat.  Much less work down the road.

 

Check out the Devlin boat pictures - painted can be attractive.

 

Sanding will not remove blush.  Use dilute vinegar and water, soap and water, or just clean water.  Check out the instructions for paint preping at the Chesapeak Light Craft site for guidance on removing blush.  You do not need to use solvents like acetone or alcohol.  Blush is water soluble.  Sanding will not remove blush.

 

Sanding to 320 before varnish should be fine

 

Wear nitrile gloves, eye protection, respirator with organic vapor cartridge, long sleeve shirt and pants.  Epoxy hardener is a strong sensitizer.  Remove epoxy from skin with vinegar and soap, not organic solvents.  If you use rollers or chip brushes don't clean them...just toss them out after hardening.  Before complete cure...which may take a week...dust from sanded epoxy is still sensitizing so wear respirator and gloves when sanding.

 

I've probably forgotten a few things, check out glassing instructions at the Montana Riverboats site to double check.

 

Go for it...it is not particularly difficult.

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Permalink Reply by lhedrick on April 18, 2011 at 8:25am

When wetting out glass or kevlar fabric, the more time you have the better.  I would also recommend that you plan your work so that no sanding is requierd.  With slow epoxy and a cool shop (50-60F) you will have a recoat window of 3 - 4 days.  The epoxy will cure slowly and new layers will lock together with no sanding.  In summer with shop temps of 80 you will only have a 24 hour window.  

 

If you are using heavy 15 oz biaxial glass you need slow epoxy, a cool shop and extra hands.  The stuff is very difficult to wet out.  I have done it by  myself in a cold shop and it's still difficult as the epoxy start thickening before you get the heavy cloth wetted out.  I would recommend 2 layers of 10 Oz instead of 1 15-17 oz.  It is easier to do.  It helps to seal the plywood with a coat of epoxy the day before.  When cured to touch and cloth will not stick to it then apply a new coat of fresh epoxy and get help setting the cloth onto the epoxy.  Smooth it out from the center to the edge.  While one person is getting is flat the other should start mixing the next batches.  Keep it moving.  

 

If you plan on doing a clear non-painted finish be carefull when you poor the epoxy onto the surface of plywood.  The new epoxy will soak in quickly at the point where it has been poured into place.  As it starts to harded it will soak in more slowly.  This often leaves a mark.  Example dump the batch in an area.  Then place the mixing cup upside down 2 feet away to get all the epoxy out.  Now you go to work and start moving the epoxy for a few minutes.  When done working the area you go back to the cup and pick it up.  There will be a ring of epoxy on the surface where the cup was.  After completing the job that ring will show up and there is no way to get rid of it.

 

Work quickly and get the epoxy moving as soon as you dump the batch. If you will be working in summer use nothing but slow hardener and work at 7:00AM before the heat of the day.

 

L

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Permalink Reply by justin nicola on April 18, 2011 at 2:05pm

thanks guys.  shop is climate controlled (window unit, insulated walls, not rafters) and i am between projects right now, so ive got the time.  using 6 oz mat.  poured first layer of epoxy a little while ago to soak into plywood.  made a bit extra, and was amazed at the fact that the leftover (solid) epoxy was warm to the touch through the container.  spoke w/ tech support at west systems, and would highly recommend them.  spoke w/ a real live person w/ no waiting who was extremely knowledgable and helpful.  their number is 989-684-7286.  my main fear is blush on the wood finished portion.  they told me not to wipe down w/ min. spirits to remove dust.  any ideas on that one?  i am using the extra clear hardener, and i did save an inch of it in the container to see how it would look clear (passed the 4" eye test).  they also told me to use 1 coat only of epoxy on the wood surfaces (before a million coats of epiphanes).  thoughts on that?  they also said to sand to 80, which sounded low to me.  as for dump mark rings, most of the big sections are on the outside, so hopefully that wont be an issue on this build, but thanks for the warning.  id be mighty upset w/ a ring stain on the side...

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Permalink Reply by lhedrick on April 18, 2011 at 4:38pm

I wouldn't worry too much about dust.  We mix dust type stuff into our epoxy all the time, ground glass, wood flour(dust) other fillers.  Just brush it off after sanding.  Vacuum or air jet to get the rest off.  Don't use mineral spirits.  If you wipe down do it with acetone.  Acetone is used in the manufacturing process of epoxy and it's flash point is so  low it's all gone in no time.  Remember that West, System 3, Raka don't build epoxy.  In most cases epoxy resin is built by major chemical companies like Huntsman.  The distributers dilute and package.  The building blocks of most epoxy resin will all be the same.  Built up from acetone ->bisphenol->epoxyresin.

 

As for blush, it mostly only shows up with higher humidity.  Here in Utah we often have summer humidity of less then 10 percent.  I have never seen blush after using 75 - 100 gallons of epoxy. 

 

As for 80 grit that kind of rough and you could see swirls but,  I usually stop at 120.

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Permalink Reply by Eric Loudenslager on April 18, 2011 at 4:31pm

One way to avoid the S curves and container rings from pouring epoxy on the glass or wood is to pour it into a pan (pie pans work well) and pick the epoxy up on a foam roller and apply it to the wood or glass.  I use the yellow 1/8 nap roller covers.  That application strategy also slows down the epoxy cure.  If you leave the epoxy in a cup it can heat up fast and cure quickly.  Many epoxy manufacturers advise against mixing in glass containers 'cause the heat from the mix can break the container.

 

Sanding to only 80 grit seems like it would leave scratch marks in the epoxy that would show through the varnish.  Best to test a scrap piece. 

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Permalink Reply by justin nicola on April 18, 2011 at 5:40pm

thanks guys, i am so ready to tackle this tomorrow.  i will definitely go to 120, minimum.  l hedrick, im in south carolina, we know a thing or two about humidity, but boat is going to ct, w/o too much.   heading to lowes in the am for acetone and rubber gloves, and then im rocking and rolling.  ill get some pics up then.

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Permalink Reply by Rick Newman on April 18, 2011 at 6:04pm

J

Justin, how long has it been since you put the first coat of epoxy anywhere on the boat. I believe that the eighty grit sanding reason is to provide a mechanical connection for the epoxy it it has over 72 hours since you last applied it. Within the 72 hour window you can still get a chemical bond. I know you have had good luck with the customer service folks at West Systems. I have never dealt with them so I have no opinion, however System Three has a good, free "Epoxy Book" that you can read online. While the chemistry might be different between the two products I am willing to bet the application techniques that System Three writes about are applicable to both. Here is the link: http://bristol29.com/Sources/system%20three%20epoxy%20book.pdf. I have been doing quite a bit of epoxying and have found their information useful. Get yourself lots of gloves, a plastic squeegee or two and a big bag of rags. If anyone has Biosolve in your area it is a great solvent without the hazards and potential contaminates that modern acetone is rumored to have.

 

Good luck on your build, it looks really solid! It is currently snowing here in Spokane, makes it hard to get epoxy to cure, my climate controlled garage/shop only needs heaters, since I insulated the walls and ceiling as well as sheet rocking the walls it has been easy to heat and doesn't get too hot.

 

Happy Waves to You:

 

Rick Newman

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Permalink Reply by justin nicola on April 19, 2011 at 11:10am

rick, dont worry, i was running heaters in my shop when this project started.  i have exposed, elevated ribs that needed to be sealed before they were fastened, so i needed steady temperatures back in january. 

 

as for this fiberglass work, it was no big deal.  went out to check on my first coat last night before bed, it was dry (no tack) so i decided to knock out the actual glass laying.  it took a bit of doing, but i was done by about 2 am.  just sanded it down to 180 and put a third coat on.   may try to get one more coat on to get it extra smooth, i have plenty of epoxy still.

 

im not sure how to proceed as far as order of operations at this point.  boat still has "skirt" on it, and the area that is ready could be painted now, then the whole rest of the boat needs to be epoxied.  we are having a relatively cool stretch, so it may make sense to do all the epoxy now, but then i will have to retape everything. 

 

as for painting a boot stripe, anybody have any great tips to ensure an even line.  i was thinking of using 1" painters tape, laying three strips edge to edge the length of the boat, then removing the middle strip.  thoughts?

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