Out of the bag finished

From a thread I started to hijack…

From Benny1… The 2 surfaces of the bag don’t meet because there’s a whole rocker table in there with the board… if you look at the photo way up above, you can see the rocker table & board in the bag. When I took that photo, the rails weren’t on yet, but its the same as if they were. I’d even tuck the bag tighter around the rails if they were on & shaped, because they get a radius, not a square edge…

I brush some resin on the rails first - they’re dry balsa at this point, while the deck & bottom are already glassed. Brushing does 2 things - helps the small laps stick to the small-radius rails, and also fills cracks & pores so the rails don’t suck resin out of the cloth & make dry spots or air bubbles.

Glass the bottom, wrap the rails (small freelaps) pull tight. Lay wax paper on the bottom & flip. Glass the top - but I don’t cut the cloth until its already stuck down & filled with resin. Then cut another small freelap & tuck it all the way around. It sticks really easy into the cloth that’s already on the bottom & still a little wet. I warm the resin a lot, so the bottom is definitely gelling - careful with that, though.

Then pick it up, peel off the wax paper, put it down on the rocker table, slip the whole works into the bag.

Pull to about 5 in Hg and shut down vac. That’s enough pressure to mold the bag around the edges to hold all the glass tight, and to squeegee air bubbles & extra resin off the deck. The bottom takes care of itself on the (waxed) rocker table. Then fire back up the pump & pull to 14 or so. Leave it all night with a couple of halogen drop lights suspended above - just enough heat to set it nice & hard.

This morning, I shut down vac (it probably hadn’t cycled in hours - the pump was cold - and after the epoxy is set, there’s not much movement anyway) and inflated the bag. I use a schrader valve for my bag attachment so I can pull vac & then inflate too - inflating the bag pops everything loose without having to pull & stretch the bag film by hand. It also looks cool to see the board inside a huge yellowish sausage :slight_smile:

I ended up with a little bead of glassless resin around the lower perimiter of the board which easily surforms off. I also got a couple dry spots on the deck where I pressed out resin too aggressively - but with very warm resin & the tips of a paintbrush I can fix those :slight_smile: Otherwise, mirror shine on the bottom; top finish that can go straight to 400 or 600. Works for me :slight_smile:

First off, Benny, You Da Man!

Rocker Table or not, you still have two surfaces meeting. Well actually three, the bag, table, and board must all meet somewhere. I’m thinking my problem is one of two things, I’m skimpy on the resin or else my 30 mil bags are just too thick to get a small enough radius at the triple intersection point. The problem I see is the vacuum sucks the cloth off of the rail in the intersection zone, leaving a void along the entire rail line.

Onto the next question for the masters

Benny noted the “waxed” table. Does this provide a different/better finish than the surfaces that contact the plastic bag? Instead of wax, a sheet of plastic could be placed under the board and reused over and over. Definitely easier, but is it better?

I really like the use of the lights for a quick and easy post cure. Have you measured the temperatures you achieve?

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Benny noted the “waxed” table. Does this provide a different/better finish than the surfaces that contact the plastic bag? Instead of wax, a sheet of plastic could be placed under the board and reused over and over. Definitely easier, but is it better?

Here’s what Ben is talking about. It CAN provide a much better finish, but its not without its own drama (which at times I wonder if the benefits outweigh the problems).

What’s the material on the table surface?

When finishing in the bag, there’s not too much resin to work with. Is anyone having issues with exposing the cloth during the sanding/polishing process. To my eyes, it looks like the weave just wants to jump out of the matrix just at the thought of being sanded.

In the traditional process, the hotcoater leaves a bead that the sander uses to create that knife sharp edge in the tail. Is the bag finish going to do this?

I ask all these question because I’m just about ready to put the outer layers on my new board. I have no problems with hand layup, but in one word, “Ughh”.

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When finishing in the bag, there’s not too much resin to work with. Is anyone having issues with exposing the cloth during the sanding/polishing process. To my eyes, it looks like the weave just wants to jump out of the matrix just at the thought of being sanded.

Yep, there’s not much room for error. However, if you do it right then there’s not much to sand.

I’m using 100 gram/3 ounce cloth, and I don’t really get the mirror finish that everyones talking about…

It comes out flat and with a bit of shine, but when you look closely, there are gaps between the fibres, that would act like pin holes.

Look sort of like i’ve glassed the board with mosquito mesh.

Maybe the weave on the cloth i’musing isn’t tight enough, or i’m making my lam too dry.

I really use the minimum of resin, less than 1:1.

I might try cranking the pressure up on the next one, maybe it will squash the fibres so they flatten out like ribbons, and close up the gaps.

Anybody have the same results? any thoughts?

Kit

Scott, I like the mould release wax because there’s no chance of a wrinkle. Put it on, wait 90 seconds, buff it off - repeat 4 times for the first coat. I’ve had problems before with plastic sheets, or peel ply, or even mylar wrinkling up under vac. And if that’s between the rocker table & board, you’ll never even see it. :frowning: I’ve had peel ply wrinkle up the cloth into a fold and I ended up with a fold of cloth that was hovering over a board like a sail. I had to cut it off & do a ding repair…

If you’re doing your final glassing on a board of which you like the rocker, Just do it in two hits. Lam the bottom, put it in the bag with no peel ply or absorbent and not even the rocker table. Pull to 4 or 5, shut down, gather all the bag on the opposite side of the lamination, smooth out all your bubbles & wrinkles, and pull up to only around 9 or 10. You won’t harm the rocker or compress the foam at that pressure, but its certainly enough to get a very smooth finish…forget the table, just put the board & bag on your glassing stands.

Next day, do the other side the same way. You won’t have to grind laps or anything. Sanding? Nope, not that either :slight_smile: Unless you have to rough up the tail to tape off a dam & build up an edge. But I have a trick for that too - do it when you hotcoat whatever patch you put on over your fin boxes or glass on fins :slight_smile: If I want a tail edge, I usually just use a whole tail patch as a finbox ‘cap’ out to the rail. It needs a hotcoat anyway…so I tape off the rail & leave the tape’s top edge as high as the (upside-down) deck, not at the apex of the rail. The hotcoat fills that right in & its better than plain resin bcause its actually mostly a fill coat for the fin area patch. If you still want it to flex, use 2 oz cloth & flexible resin like 2020 :slight_smile:

My digital thermometer sitting next to the rocker table, under the halogens, said 67* f at 6:20 this morning. Not warm, by any means, but enough for the epoxy to set up right. My garage is insulated in the ceiling only & the walls are plywood, studs, and siding - that’s it. When I got in the truck to go to work at 6:45, the truck’s outside temp thermometer said 41*. I’m glad I used the halogens :slight_smile:

Benny

if you got the halogen over the board, what’s keeping the plants happy?

:wink:

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I’m using 100 gram/3 ounce cloth, and I don’t really get the mirror finish that everyones talking about…

It comes out flat and with a bit of shine, but when you look closely, there are gaps between the fibres, that would act like pin holes.

Look sort of like i’ve glassed the board with mosquito mesh.

Maybe the weave on the cloth i’musing isn’t tight enough, or i’m making my lam too dry.

I really use the minimum of resin, less than 1:1.

Would act like pin holes? Nope, those ARE pinholes. I get the same problems. Many are pretreating the balsa first, this disallows saturating the balsa with resin though. I’m seeing better results when I only apply one side of glass when making my skins. Note some of Benny’s older pics, his breather cloth covers almost the entire area, this probably allows a good escape path for the air entrapped in the balsa. I’ve been skimpy on my breather and maybe am paying the price. You basically have two options now. One, you can cross your fingers, heat up a hot batch, and stipple the resin into the pin holes. Two, sand the heck out of the outer layer and lay down a second sheet of cloth. This provides the added benefit of a much stronger board. This is the approach I’m taking on my current project. Resin ratios I’ve tried 1:1 with 4oz cloth and could not get close to thourough saturation, I’ve bumped my resin usage up to 1.5: 1. Add in the wood soaking up resin and you can see that 1:1 is tough to achieve. I still haven’t decided whether to use the bag finish yet, tonight it’s finbox router time…