Together with my shop-vac I'm going to use them to get a tight laminate on the hull. The shop-vac for the bulk air removal and the Welch for the rest.
If using a vacuum pump you must put the exhaust outdoors, the sucked air flows trough the oil and out the exhaust. A very fine spray is produced, this is invisible but settles on everything in your shop. Also on the parts to be laminated, they will not bond with your polyester or epoxy anymore.
I tried the Welch with a bathroom scale in a plastic bag, had to stop it at 175 Kg.(±380 lbs) the scale was bending in the middle and jamming the inside. The surface of the scale was 10"X 10" , do your math! Pressure enough.
But . . . . . This only works with small parts. As I found out, it's hard to get BIG vacuum bags totally air tight. This pump has a lot of sucking power but not volume. This means that if there is a small leak somewhere in the bag it will not have the capacity to keep enough vacuum. To get over this problem look further down on this page.
The epoxy I use is from "SP Systems" in England. They do a lot of sailing and racing boats, like America's cup yachts and Sunseeker. They do also something in Stealth stuff, but that's hush-hush. I have to use epoxy and not polyester because of the solvents in polyester.
Solvents will reduce Styrofoam into sludge in seconds.
The matt or weave is also a bit different, there is a coating on both types but the solvent in polyester asks for a different one than the one for epoxy, polyester-glass matt can be used but you need the slow curing epoxy to get a good bonding.
Epoxy versus polyester
The two are completely different.
Polyester has the smell of styrene and that is HARMFUL. It is labelled toxic. It needs the hardener, which is solvent and reagent for the resin itself. So, more hardener means faster reaction. Less hardener means slower reaction, but within limits, it will all get hard. It will always need some days to harden completely! A normal polyester takes 7 days! The hardener will not react with the resin; it only starts the reaction of the resin with itself. Polyester is solvable with “normal solvents” although slowly.
Epoxy is harmless because it has no solvents and does not evaporate. Some smell a bit like ammoniac (rabbit burrow). If the resin and reagent (we call it hardener) mix is not exact up to specs, it will never get its optimum quality and will stay soft or sticky. Opposite to polyester, the two react with each other. On a molecule basis it needs a perfect match (cross-linking) which is strictly set by the manufacturer (example 2.8 : 10 weight ratio) If you are out of this mix balance it will never harden. In contrast to polyester it is set after the reaction is finished definitely. Normal is two hours. The “slowest” I could find is 8 hours. Epoxy does have sometimes a irritating sense on the skin and after curing can’t be solved with a “normal solvent”
There are epoxy types that have solvents but they are for coating purposes only.
Use always protective clothing, goggles and gloves.
After some thinking I have to add: Be careful with all chemicals and treat them as dangerous to your health
Working with old stuff and the two together.
Polyester keeps on reacting the rest of its life, so it gets more brittle if it gets older. If you laminate Polyester over older polyester there will always be a difference in structure. This accounts for the reason that you can peal it/some off later. Now, the younger the poly-laminate the better the bonding with a new layer. Polyester is a structural mass that sticks a 100% to itself, if it is in the same (wet) state. If the mass is not the same (like it's older polyester and already hardened) it will bond less. If the surface is (hardened) epoxy the same applies. Lets say it will stick some, but not bond or glue.
You can not mix the two in a wet state.
Epoxy however is a "glue", it will break just a bit easier than newish polyester and is, after curing, at a state that will not change any more (unlike polyester). But being a glue it makes the glass layers a stronger material than with polyester. (fact. epoxy-laminate = stronger than polyester-laminate).
So, being a glue it has the inbuilt property of sticking to a lot of stuff (like cured polyester). This accounts for the better bonding between old (cured) polyester and fresh new un-cured epoxy.
This is the layman's explanation of the topic! As I heard it from the factory people from SP-Systems. This is how I remembered it (ha ha)
In short:
New polyester on old polyester = Soso, only within months (good prep needed)
New polyester on old epoxy = NONO
New epoxy on old epoxy = yes (good prep needed)
New epoxy on old polyester = yes (good prep needed)
"old" being cured laminate.
The whole vacuum pump setup The top bolt adjusts the pressure and the bottom eye the cut off moment
This is the vacuum buffer tank 60 liters Some tools I use After use ! !
The BIG pump
As I said above to keep good vacuum is not easy with household materials.
The best, cheap, result was if using the transparent tape, about 2" wide. This has the advantage that you can see through the tape if the folds and wrinkles are well taped/closed. Duct tape is $$$ and it will rip the bag to shreds after you're done, preventing you from using it again.
The second pump I got for free. It's a vacuum cleaner pump from a central vacuum cleaning system. (This is a system that runs through an office/house with pipes and has connectors all over the place for the hose.) The unit is loud and produces a lot of heat. Made by Beam Industries in Webster City Iowa. It uses 6 amps and 230 volts. It sucks over 55 liters a second (not beer) and about 25% vacuum. This will rise till 30% if all is heated up till 113°F this increases my shop temp and so speeds up the curing. Isn't that cool??
Well not THAT cool, because it could over heat if running a long time. Although it has it's own cooling fan the pump itself creates a lot of heat. I made a way to create adjustable air/vacuum leakage to control the pumpheat.
Here you see the pump pulling just over 25%
vacuum, the whole is clamped down between rags to prevent it from walking un
accompanied through my shop and the rags are to keep the resonating noise down.
This one shows the box I made with the hose
connection. In this connection I made holes with a ring with aligning holes. I
can open and close the holes by turning the ring. This is needed if the temp
runs too high.
Laminating Stuff
This is easy if there where no corners and no bends and round forms in the foam !! But as we all know there are !!!! One of the most laborous jobs was the duct. This is large and round one way and tapered the other way. The only way toget it all done was to make a milion cuts to get it to follow the shape. Then line all the pieces up and make a strange big bag to get all places the same pressure. We did this laminating in three sessions. It takes a lot of time to get all things done, so we decided to take it easy and split the work up. Otherwise the epoxy would have cured under our hands.
The small parts
All the same procedure, using the small pump and pre-made bags. I found out that large garbage bags are real good for laminating the small parts. Because there is only one side to get air-tight.
Now the hull
Logistical nightmare, because of the size and all the things you need to have lined up. Once you start mixing the resin, there is no way back.
First the hull surface has to be prepped. This means roughed up a bit and clean. Next is the cutting of the glass, peel ply, breather, ripp cloth and finally the bag. Next is to check if all is present in the tool department. Like cups, brushes, rollers, squeegees, resin, hardener, scale, gloves, scissors, knives, sticky tape, pump, hose with holes and probably something I forgot too !!
I used a vacuum meter to check on the pressure. This is good for the peace of mind, just to know that there is enough vacuum and not to much also.
The resin I use allows me to mix the different hardener types. This means that I start with a mix that will cure slower than the last batch I make. The batches following the first will have gradually more fast curing hardener mixed in. Be sure that the epoxy you use can handle this mixing if you want to use it.
JUST SOME BRANDS CAN HANDLE THIS. READ THE SPECS OR ASK YOUR SUPPLIER.
Sorry, no pics of the laminating itself. I had my hands full with sticky stuff.
In the left picture you can see the making of the top of the bag, the bottom was under there before we started laminating. For the bottom we used thick PE. This because it had to withstand some rough handling. The top half is real thin; this follows the shapes of the hull real good and provides an even pressure and less pronounced wrinkles after curing (meaning SANDING !!)
OK, the bottom is almost done now. Be aware that there are some imperfections after curing/un-wrapping the package. Just sand it away and make the repairs. Most of them are in the difficult corners and next to the hose. Paying attention to these spots made me have less repairs, but they still pop up now and then.
After the unwrapping and filling and sanding and filling and sandingand filling and sanding, I painted the bottom !!
I know, I know, you don't have to, but the idea of having a lot off pinholes in the bottom did not agree with my sailing background. A watercraft shoud NOT have holes in the bottom, full stop !
AND it looks nice . . . . . . . painted with epoxy paint.
Now it's time for the top side. After making sure that all hard points are in place and the floor fitted in the cockpit area, we did basicly the same as with the bottom. Prepare all glass layers, peelply, breather, pump, hose and the bag. Bought some more epoxy (ouch! $$$$) and asked my friends to come over on a saturday morning to lend me some hands (6 to be precise)
The result was real good apart from some small dry spots that need some extra care. All threads in the hard points need some cleaning up anyhow so no harm done.
the atmospheric pressure is working dryspots
The front is to be done an other day. This "simple" flat piece took the four of us 2 hours from start to the coffee afterwards.
Not all is well at the attic today !! I made the windscreen frame and thought that is a nice evenings work to laminate. With this in mind we made all matt/weave, breather, peel-ply and bag the other night.
Last night I/we laminated the windscreen frame.
After all was wrapped I could not get good vacuum, but decided it was enough and
went to bed at 3 am !
Somehow the bag ripped at a taped seam during the night. This morning when I
came in the shop it showed instantly, because the bag wasn't tight anymore and
the vacuum meter was on zero. The damage is yucky, a lot of loose glass an
bubbles all over. A heap of work to get all the loose stuff off and repair it.
So, not all is/was well in the low lands.
There is a lesson here ! ! . . . . . . DON'T SLEEP
AT THE JOB !!
The walls of the cockpit where straight forward and I decided to laminate them seperate from the hull and glue them on later. This way I had an easier job laminating, filling and sanding. There are two sides and a back. This is one side.
I put one sheet of plastic foil on the table and stapeled the corners to the tabel. Laminated both sides and wrapped it. Finaly I sealed it with a second sheet of foil, using vacuum tape (the yellow lines). Don't forget to undo the staples before you start pulling vacuum. I took care that the vacuum hose did not touch the object, this way I prevented epoxy-ridges and so some extra sanding.
Having done this I could use the small pump and get a nice high vacuum ( -8.4 lbs/sq" or -17" mercury)
THE NOSE-JOB !!
The front of the craft was a mountain of work in prep and logistics.
I was at the edge of the bagging time when I got the vacuum on it, but it all worked out real nice. I had only three spots that needed some cosmetics after curing. Next(if ever) time I'll do this with one pair of hands extra or in two sessions.
The complex shape is the time consumer here.
Left are the glass sheets all cut to shape and numbered. Right is the nose before the job, with two surgens.
The Bag-mess in the duct with some
vacuum hose.
SANDING THE CURED STUFF
Straight forward would you say. Yes eccept its darn tuff stuff and it has an itchy side effect. I asked on the Hoverlovers Yahoo group: click to go there--> HoverLovers group website how my forum buddies where coping with that and what they did to prevent the itchy stings. This is what I got till now.
Question on Hoverlovers:
What do you guys
do, to prevent this glass fiber stingy itch. Other than don't use it !
You all used it, all sanded it so you all know what I mean!
Yeah, you guessed it, I sanded a couple of hours !!!!
Grrrr, itch sting itch itch!
Some answers from Hoverlovers members.
>
David Bosworth
I use baby powder on any exposed skin. Works great! it's an old insulation installers trick,,,,,,,,works for young guys too.
>
Pat Conrad
Rub Crisco all over your body first.........lol.......Actually if you use some hand cream or such on exposed skin it will help some.
I get the glass itch and swelling on my arms if I don't keep my sleeves buttoned down good, but that only happens if rest my arms on the hull where the edge of web is exposed.
>
Jake Westfall
If you have an auto parts store handy you could probably pick up a tyvek suit. They are thin and do a good job of keeping fiberglass dust off.
>
Tim Jean
Wash the effected area with good strong cider vinegar, than shower. Should go away.
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Chris Padgett
Prevention is
indeed the name of the game! I wear disposable gloves, a long sleeve light
(cheap) jacket on top of a long sleeve shirt, and either a dust mask or a full
respirator, depending on how long I'll be sanding and how much dust I'll be
producing (respirator is more comfortable and seals better). During sanding, I
try to keep a lid on the amount of dust in the air and around whatever I'm
sanding by shopvaccing me and the surrounding area every couple of minutes.
I've had reasonable luck with this. You do have to be careful not to put your
arms down (maybe the worst thing you can do!).
>
Jerry Coffman
Ya
know, I've never had a problem sanding fiberglass or hanging insulation. Did my
shop in the heat of summer and it never bothered me. When I sand a craft, I get
it on me and if I lay my arm on the table, or put a coat or other long sleeve
article on, I can feel the pricks up and down my arms, But a hot shower and it's
all gone. I know what they say about the shower, but I take it as hot as I can
stand it..
The only problem areas I have it in between my fingers. Duct tape or other very
tacky tape works wonders on that area.
>
Lance Sloan
I use baby powder or regular talc and it works wonders. I learned that trick back in the early 80’s when we re-fiber glassed my step dad's (Bill) commercial fishing boat. The supplier shipped a 45 gallon drum of talc with the fiberglass order and when Bill asked why they shipped a drum of white powder the wholesaler told him that the talc was standard practice in the marine industry to prevent the itch while sanding.
>
Wendell M. Jones
Around here we
use corn starch-rub it onto the itchy areas and let it grab
the fibers, brush it off, works for me and work group.
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Richard Grom
This may not take the itch away but will prevent future itching...quit sanding!!!
Seriously, when sanding is finished for the day, afternoon, or whatever. Take clothes off and take a cool shower. Not hot or cold. A temperature that can be handled. A cool shower prevents your pores from opening up and fibreglass setting in. The water takes whatever sanding particles are left on your skin. This works for me.
>
Brian from NZ
To stop the itch arriving in the first place, use an old sparky trick, when I have to go into an attic insulated with fibreglass insulation, I apply talcum powder to all exposed skin surfaces. You can use the pretty smelly stuff or just plain non scented... Your preference lol..... but this will also work with sanding as well.
Here is some Epoxy paint
Took me three coats' to get it like this, the filler kept on being visible through the paint.
aint
she pretty?
more info is coming.