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I thought I'd try to post a thread on bagging.

I think I can pull it off.

First thing is you need a flat surface with no leaks. This table is 1" mdf with two epoxy lifts sanded to 400 grit.

The back side of the table holds the bag. The bag is held on by butyl 1/2" wide. I also put my hose there on the table edge.

The table must be waxed 3-5 times before initial use. Depending upon the peelply used; waxing a single coat each time may be required. My peelply eats wax and so waxing every part is necessary or you have a nightmarish 2nd part pull and the third usually damages the piece on removal.

Here I am waxing.

An extra final pass up the middle is smart. See the circular pattern. A sheetrock trowel to remove any stuck epoxy.

Nice FallGuy!!! Jeff

Thanks for posting, I considered asking some questions on your build thread about it, but didnt want to cloudy it up with dumb questions

fallguy1000 wrote: ↑Thu Oct 08, 2020 12:15 pm This table is 1" mdf with two epoxy lifts sanded to 400 grit.

What does epoxy lifts mean? You put 2 coats of epoxy on it to seal it and get your smooth surface?
The mdf holds together well enough without a thin layer of glass to keep it from crumbling over time?
What kind of wax do you use?
What do you use for a vac pump?

What is your layup from table to top bag?

-bag
-peelply
-x layers of glass
-foam
-x layers of glass
-peelply
-table
????

Dewaxing is next. I like to go relatively soon. Not so much for a patience issue, but I find it easier physically. Once the wax dries hard; it is harder to dewax.

I tried commercial waxing equipment, but found by hand is the best. Except it is a little taxing.
Start with old cotton sheets. Use a circular motion. Be nice to your back. I do one side at a time. Turn the dewaxing rag and shake it out now n then. A pita, but needed. Here I waxed and dewaxed an 8 foot section by 4' wide in about 20-30 minutes.

narfi wrote: ↑Thu Oct 08, 2020 12:30 pm Thanks for posting, I considered asking some questions on your build thread about it, but didnt want to cloudy it up with dumb questions

fallguy1000 wrote: ↑Thu Oct 08, 2020 12:15 pm This table is 1" mdf with two epoxy lifts sanded to 400 grit.

What does epoxy lifts mean? You put 2 coats of epoxy on it to seal it and get your smooth surface?
The mdf holds together well enough without a thin layer of glass to keep it from crumbling over time?
What kind of wax do you use?
What do you use for a vac pump?

What is your layup from table to top bag?

-bag
-peelply
-x layers of glass
-foam
-x layers of glass
-peelply
-table
????

No questions will be deemed dumb.

There is no glass on the mdf table. The two epoxy lifts were done to ensure no leaks. If you look at the picture; you can see some fairing compounds. This table was formerly 34 feet long. Seams at 8 feet were epoxy bonded and faired flat. The epoxy lifts were done to make a perfectly smooth and flat surface. I used about 48 ounces of epoxy per lift. I wanted to make sure the coating leveled out nice.

I use Grignard Mold Magic Release wax.

I purchased two used Welch Lab pumps. I would not recommend them. I recommend buying two commercial vac pumps from a company specializing in veneer vacuum bagging. The welch pumps are super expensive to repair; more than the cost of a new, modern pump. You need a continuous duty pump. Slow epoxy stays under vac 6 hours. Tropical epoxy is under vac 9 hours. Then the part stays on the table 8 more hours (usually overnite) before demoulding. The reason for two pumps is my components are really expensive. The epoxy in the parts I am building is about 50-100$. The core is the same. The glass less. The labor is big. I figure the current parts would cost about two days lost time if I have a pump failure.

The large hull panels would cost about $2000 if we had a failure. We did blow a belt once and switched pumps. Right now, one of my pumps is leaking...super costly to repair.

I will explain the stack in the pictures forthcoming.

After waxing the table, you need to peelply the mould. I peelply always; even for a single sided lamination.

The side of the lamination is an issue. I always like to laminate outside up or any radiuses up. Otherwise you need to placehold which is another discussion.

You get a piece of peelply smaller than the table, but larger than the part and tape it to the table. I don't like this peelply, but I have a bunch of it, I prefer the redline stuff used by airline industry. It releases from the part a bit easier.

I am rolling a bit far for a table full of scrap glass. The part to glass is 55" high, wider than the table. Is 38" high, so a piece of peelply 44" is about right. Cutting is done with an electric shears for a projdct this big. I use gorilla tape to tape the peelply down.

I used to use masking tape, but this peelply is super slippery and only ship tape works.

The peelply must be pretty tight or the bunching will appear in the part.

Tape all around. Mark the part location with a sharpie. This is to know where to pour epoxy. Foam core is held together with plastic raptor staples. The gun is $225. Under 2 boxes of staples were used for the Skoota. Foam is easy to repair or add onto. Epoxy fills the seams.

I am actually going to laminate two pieces in this go.

The first steps are the same.

I don't show it, but a second piece of peelply is made for each part for the top. That piece is rolled onto a tube. Roll it on end to start. Roll off start to end!

The second part. It has a radius. This is best laminated up or there will be no glass on the round. Three inch cardboard tubes are used a LOT. Here I am rolling up the top peelply onto cardboard for easily rolling it onto the wetted part.

At some point, you need to cut glass for your parts and roll them onto tubes. You can overlap glass on the bottom and it will be pretty flat.

I will post pictures. I will avoid a caption. The glass is carefully marked so you can follow your work.

There is not a lot of time for trouble or confusion.

Disregard the picture of the breather fabric. It is in here by accident.

Next is to measure and cut release film. I already had a piece done. It is cut for the whole area under the bag. It is reusable. This release film has a pinhole on 10mm centers to bleed resin to the bag. It also keeps the breather from sticking to the peelply and table. It is bleeder release fabric.

Then the breather film is also cut and rolled onto a tube.

Next is to calculate the resin needs. Since I am working alone today, I will pour a bit heavy.

Calculate the weight of the glass.

Use about 120%.

Use about 25-35% to wetout the core.

Here is the calc for the small piece. 15 oz of fabric at 120% is 18 oz of resin and about 6 oz to wetout the core. The core bottom side must be wetted to avoid dry sucking the glass. Too wet and it will leave air pockets when the vac smushes down on it.

This is 12 oz glass. I use about 60% of the pour on the bottom and finish the top.

For simplification, I will be making 3 mixes of about 24 oz of resin each time today. So not by the book so I can try to get a few pictures.

Gum tape is applied.

Leave the papers on 3 sides.

Any drip of resin renders the bag leaky. A realnightmare.

Any bits of glass threads are also leak hazards.

Cut gum tape with a scissors. A knife is a mess.

Ready to wetout! A roll of vac tape..1/2" Threads are bad and will leak; work area must be clean. A finished corner. Put tapes all down. Lift tape to bond the gum tape cuts. Sorry; these are a bit out of order.

Wetting out is always a challenge. 12 oz fabric is really friendly. 60% under, 40% on top

Tools-consolidation roller, 9" roller cut to 3" on a 3" roller frame Starting at 3:12pm The bottom of the small part is 60% wetted. The underside of the core must be wetted to avoid drysuck. If translucent; you can move to next step. Other big section wetout. Wetter on reverse and flipped. All tops are wetted awaiting top glass.

The top glass wetout is done (no pic), then the peelply is rolled off a tube flat onto the part. No bunching is permitted.

Then bleeder release film.

Then breather media.

Then wipe any drips. I almost always have them; none today. No epoxy around the bag.

Then deglove and let hands dry. Sweat on the bag is a vac leak.

My pics are out of order. Deal with it please.

Then fold the bag over.
Deglove and dry hands before handling bag. Wet gloves are trouble sealing the bag. Remove them. Remove drips Last item in the stack is the breather that allows vac pressure to moderate over the part. 2nd to last item is the bleeder release film. It should be larger than the peelply. The peelply goes above the wetted glass. I do not wet it. It must be perfectly flat. Gentle pulls remove air bubbles.

Laying the bag is sort of its own science. You can google pleating a vac bag and watch a video on it. This bag is a 3rd rounder. They almost all develop minor leaks by the third pass.

This one had a leak...somewhere. I gave up on it. My vac pump is directly under the work. If you want a better setup; keep the pump firther away so you can hear leakage.

I had the bag closed at 55 minutes. Pretty late, but was trying to get pics in as well.

Leak repairs. Bag was closed quite awhile here. Leak repair closeup. Pretty late for a 3:12 start. I was a bit slow today going to the camera. Keep the bag taut to avoid a leaky ripple. The next 3 are in reverse order. Basically, I keep the bag pretty tight. Some guys might like a looser bag for less bridging. I tolerate it. These shots are jist to show how important it is to keep the bag laying flat.

Probably a few nuances I have glossed over. This might help a few people.

Open for discussion.

So, just to understand, you are wetting out the core and glass then vacuum? You're not using the vacuum to pull from an epoxy pot to wet out?

What brand vacuum pump are you using?

piperdown wrote: ↑Fri Oct 09, 2020 7:49 am So, just to understand, you are wetting out the core and glass then vacuum? You're not using the vacuum to pull from an epoxy pot to wet out?

What brand vacuum pump are you using?

Correct. This is wet bagging; not infusion. I have the wrong core for infusion.

I do not recommend these pumps. They are too expensive to repair. A repair kit costs more than a new pump that will work.

My pumps can also full pull 30" HG. This crushes voids and drives resin content scary low sometimes. I think running at around 25" would be better, but everytime I run low I get voids; so my system of running low has something amiss. I have a system bleeder in the vac line, but I am convinced it becomes an easier place to flow out air. A friend of mine says he had the same issue and he backed off the pump after 5 minutes.

I am using Welch pumps.

I have two of these I bought used.

https://www.zoro.com/welch-vacuum-pump- ... lsrc=3p.ds

Pulled the parts today.

Why are you using peel ply on the mold surface? When I was making bigger panels than yours I would want one smooth exterior surface so I kept it against the glossy mold surface.

Evan_Gatehouse wrote: ↑Sun Oct 11, 2020 5:05 pm Why are you using peel ply on the mold surface? When I was making bigger panels than yours I would want one smooth exterior surface so I kept it against the glossy mold surface.

I tried a few panels with no peelply down and I experienced resin following the fiberglass more than I liked. The triax is 0 strand away from the core; or down. And I got a lot of deep grooves and shine.

Peelply resulted in a more uniform surface.

Because I was unhappy with quality and tired of all the rebate and relief prep; I also modified the outside to always be up. So the mould surface became the inside of the part.

Definitely could be done the way you suggest. Especially if you can get a shiny surface without grooving or air.

If I had to guess; one of my issues is running the pressure up too high, but everytime I back it off, I get air pockets on the mould side.

fallguy1000 wrote: ↑Sun Oct 11, 2020 8:01 pm

Evan_Gatehouse wrote: ↑Sun Oct 11, 2020 5:05 pm Why are you using peel ply on the mold surface? When I was making bigger panels than yours I would want one smooth exterior surface so I kept it against the glossy mold surface.

I tried a few panels with no peelply down and I experienced resin following the fiberglass more than I liked. The triax is 0 strand away from the core; or down. And I got a lot of deep grooves and shine.

Peelply resulted in a more uniform surface.

Because I was unhappy with quality and tired of all the rebate and relief prep; I also modified the outside to always be up. So the mould surface became the inside of the part.

Definitely could be done the way you suggest. Especially if you can get a shiny surface without grooving or air.

If I had to guess; one of my issues is running the pressure up too high, but everytime I back it off, I get air pockets on the mould side.

No personal experience here but I think if you wanted the side against the mold to come out finish quality you could put a layer of thin cloth down first, then your heavier structural layers.

joe2700 wrote: ↑Mon Oct 12, 2020 9:55 am

fallguy1000 wrote: ↑Sun Oct 11, 2020 8:01 pm

Evan_Gatehouse wrote: ↑Sun Oct 11, 2020 5:05 pm Why are you using peel ply on the mold surface? When I was making bigger panels than yours I would want one smooth exterior surface so I kept it against the glossy mold surface.

I tried a few panels with no peelply down and I experienced resin following the fiberglass more than I liked. The triax is 0 strand away from the core; or down. And I got a lot of deep grooves and shine.

Peelply resulted in a more uniform surface.

Because I was unhappy with quality and tired of all the rebate and relief prep; I also modified the outside to always be up. So the mould surface became the inside of the part.

Definitely could be done the way you suggest. Especially if you can get a shiny surface without grooving or air.

If I had to guess; one of my issues is running the pressure up too high, but everytime I back it off, I get air pockets on the mould side.

No personal experience here but I think if you wanted the side against the mold to come out finish quality you could put a layer of thin cloth down first, then your heavier structural layers.

Yes. 100% true.

And I did this with a veil cloth that I paid $450 for, but I was not a fan of the strength of it as it would come apart a bit under vigorous rolling. And it was about ? 1oz cloth, so 2 with resin. Although, thanks for the reminder, I could probably use it on a few things I am doing now.

I think a light woven would have been better.

If anyone wants a roll of veil, let me know.

Thanks for the info, FG, on wet versus infusion. I knew I was missing something