To grind or not to grind????? Help?

[B.Mac]

When laying up polyester resin & matt or cloth is it necessarry to grind the first layer that has already been laid down and hardened before applying the next layer?
I know you need to grind old glass down to pink fresh glass, but do you also need to grind "freshly laid" glass to cover it with more matt or cloth?
I would "guess" yes as the scratches allow for both a "mechanical" bond as well as chemical? But it's alot of extra work.....grind or not?
Thanks
B.MAC:D

[JohnBoy]

If its your boat then grind it. If it's someone's you don't like then don't grind.

John Smith

[H2Onut]

Rough it up

[Superdave]

If you are using laminating resin you can let it cure and still put more on, but if it were me I would rough it up.
Dave

[Techno]

No ! stop!
You have to remove the wax coating first. Then you can scratch it up. If you sand a surface contaminated with wax or silicon you just push it into the scratchs.The wax coating isn't on laminating resin, only the stuff that cures non-sticky.

[B.Mac]

Wax no wax.....what the heck??? I got regular polyester laminating resin. Are you saying that after it bangs off I have to clean it with something and if so, what? AND how do I know it's clean and ready to grind?

Starting Sat. morning I'm laying up two - 1.5 0z layers of matt and one layer of biaxel cloth in one shot over the inside of the rear transom skin. This will give me some decent rigidity in the previously cracked and weakened transom skin before I start making cardboard templates for the transom cores. After I get my cores glassed in place I can grind the exterior cracks down onto the fresh glass and build it up to repair the cracks outside.

The cores will be 3 layers of very rough ground 3/4" marine plywood with 1/4" holes drilled every 6" on center in the cores to allow for "weeping" and gas expansion as well as additional mechanical bonding. I will have a 2.5"- 2.75" thick transom when complete.

Q? Can I dilute polyester resin with acetone? In order to seal all my wood components prior to laying matt on them?

I'm lost on this wax issue please explain problem and solution?
Thanks Techno.....Please describe the laminating process for "dummies". Don't assume I know anything or I'm bound to overlook something really stupid and screw up:eek:
B.MAC:D

[Superdave]

Laminating resin does not have wax in it. That's what allows you to lay multiple layers without having to grind. The wax, styrene usually, is added to your final spray of gel to help seal the outer surface from air so it will cure and not remain sticky for months! If the resin has cured for over 24hrs you should grind it some. To make sure there is no wax you can wipe it down with acetone before you grind. I've never diluted resin with anything. When I spray clear gelcoat, I thin the gel 25% with acetone, but then I add metalflake so it gets thick again. When I sprayed the clear with no metalflake, I thinned it about 15-20% with acetone in the first coat. The last coat of GEL, wether it be clear or a color, needs 20% styrene wax added. This seals the surface from the air to harden. Before you sand the FINAL spray you need to wipe it down with acetone to remove the wax, If you don't you'll waste a lot of sandpaper. Hope this helps.
Dave
PS: this may be a sore spot for some, but Barney has some good info on his site! Also, Barney uses a product called Duratec as an addative. I've never used it.

[Techno]

Just an example of when you do want a lousy bond-
I made a mold for my cowl. Sprayed the whole thing with silicone spray- 98% pure, I hosed it down. Laminated the cowl on the inside.
When it was time to remove the mold it wouldn't come off! It was made so I would have to destroy it any way but it was suppose to release. I had to rip it off in strips and tiny pieces with a screw driver to start the release. Once I had made the mold fail the silicone did allow it to seperate from the new cowl. This doesn't give an inkling of the bond this thing still had! There was no part of it that came off like you would think, it all had to be ripped, pried, seperated and on and on.

I'm sure others have laminated right over the hardened non-sticky cured resin with a waxy surface and never noticed. This is a guess but I think the wax is redisolved into the new liquid resin.

Wood only has to have the surface freshened, you don't need to grind. The resin if it needs to be sanded only has to be scratched too. There isn't much difference to the resin between a 36 grit deep scratch and a around a 300 grit deep scratch.
If your using laminating resin then it will cure sticky and one advantage to this is you can lay the cloth or mat onto it like it was sticky paper, kind of disadvantage too since it's sticky. once wet out it isn't sticky anymore. Use this sticky thing when you need it.

Do any laminating you can out of the boat and horizontal. It's much easier and turns out better. Squeegee the excess resin off after the last laminate layed down. The bondo squeegees work pretty well for spreading the resin. Light touch and at a large angle.
Should wet out each laminate layed and not lay all of them, then wet out. one at a time.
When done the surface should show the print of the cloth or mat, if resin rich it will be smooth.
Laminating rollers help press the laminates together and remove air bubbles. If used when it gets sticky will start lifting the stuff apart instead. They work like a whole lot of tiny elves fingers.
Non horizontals and inside the boat.
Resin, laminate, resin laminate... so on. What your working on is more important than the resin you have mixed up, it's sacrificial but the work isn't.
The resin can be applied by roller or brush. The roller may pick up the mats fibers and become a pain. The brush can push both mat and cloth fibers around if used like painting. Stippling action can be used when needed, but can also add a foamy thing too.
Any concentration of resin will kick off faster than non concentrated, like the paint brush or tub of resin vs that already spread out.
All laminate MUST be wet out before stopping. No white areas. If left it won't wet out completely and will leave a gap where it was white. if it's kicking off so fast that you can't mix up more pull it off! This is very very rare.
For small manageable peices you can laminate one or all on a sheet of thicker plastic or waxed paper and lift the whole thing into place, then either remove the plastic or leave it until cured. Leaving it makes the surface resin rich but smooth. both methods are used. Should be tried before needed.
There are alot of things you can do so each job may use a few tricks.
I think the maximum laminate thickness is 1/4" close to this thickness you have to do it in stages and not all at once so the heat generated can be reduced. Not many times I know of where you'll go this thick.
-----------------------------------
Most important
If you really don't know anything and haven't done it before.
Save yourself some nightmares and sacrifice some of your materials to practice only. Take some and practice laying it up on a vertical and upside down surface. A 6" square size is probably big enough to mimic what you will be doing. Lay some on the horizontal and some on plastic then flip it into place where it would be hard to do. Try all of this on somekind of shape like a 2x4 or something, laying it just flat isn't very hard and won't teach much. The plastic trick is a flat horizntal lay up.
This will show you that you mixed up too much resin at once or mixed it with too much catylist or had it in too concentrated of a tub, it hardened before you were done.
How to apply the resin. the easiest method for what your doing.
How to manage getting the cloth flat and kind of square, the mat is easier to manage. Both want to stay away from outside or inside angles. You want to learn this before messing up inside the boat.
What happens when your gloves get resin on them and everything starts sticking to your hands- like the 3 stooges.
If you think of a trick it will probably work.
With all that this laminating is a very easy thing to do and learn. Easier to do than it seems. the learning curve is flat at the beginning but climbs rapidly, you want to do work at least on the climbing part.

[Gerben]

Hi Techno,

Were you referring to "amine blush" when using epoxy when mentioning the "wax coating". which is formed when the epoxy is fully cured?
Or does it also happen with polyester?

Gerben

[Techno]

Amine blush is only for epoxy and doesn't always happen. I think it's more likely on humid days.

The wax is put into polyester resin to form an oxygen barrier so the resin completely hardens, floats to the surface. The laminating resin doesn't have it since you would want a sticky surface and no wax to continue layup as economicaly as possible.
Some of the suppliers sell a wax additive to add to laminating resin for people who want both resins but only buy the laminating resin.

[pyro]

B.Mac, if you want to seal your wood first, here's some good stuff I have used myself:
www.rotdoctor.com
They sell this stuff called CPES (Clear Penetrating Epoxy Sealer.)
It's a VERY thin 2-part mix that soaks into the wood and preserves it forever. They tested it against other similar products and it soaked something like 10 X further into the wood grain than the others. I think their test showed that it soaked 18 inches into the grain of a balsa log. Once the wood is treated, all other epoxies and poly resins will bond better to the treated wood than they will to bare wood.

I had an area of flooring at the edge of the ski locker that started to flex a tiny bit from being exposed and weathered. I peeled the carpet back and dribbled CPES into the edge of the plywood. it soaked about 10 full 50cc syringes, drank it right up. I did this 3 times over the course of 2 weeks, and it stiffened the floor up like brand new. I also painted the exposed parts of the back seat's wood frame with it as well.

This **** is kind of expensive, but worth it.

[FCnLa]

I agree with Super Dave.

Polyester laminating resin has no wax in it.

If it has not been sitting for too long, I would just scuff it with 36 grit to knock off the "stickers" that would keep you from getting all the air out. Thats' the way I do it whether I am building new parts or a repair.

[Liqui-Fly]

How about following the directions for the particular resin you are using. Nobody here has any idea what resin you are using. You should have used epoxy and saved yourself the trouble.

David

[B.Mac]

but my supplier is out of material data sheets and I don't trust anything anybody tells me except you guys......
Thats why I love S&F lottsa helpful friendly folks:D ;) :p
I've got a 5 gal. bucket of boat builder's polyester laminating resin.
What else can I say?:D
Now lemme' go activate some mix it with some matt and slap it right in my armpits and get that over with!!!
B.MAC:D

[Liqui-Fly]

How do you know how much catalyst to mix ect?

David

[Reese]

Do not grind between coats or layers...you'll just end up with a mess on your hands.

I only use polyester laminating resin and have never sanded between coats...except when I really F&**ed up something and need to completely remove.

If you try and sand you'll probably notice the sandpaper loads up almost immediately and a gummy residue begins to form on the lamination...it not designed to work that way so don't do it.

[FCnLa]

Originally posted by Liqui-Fly
How about following the directions for the particular resin you are using. Nobody here has any idea what resin you are using. You should have used epoxy and saved yourself the trouble.

David

He said he was using polyester resin. I assumed it was general purpose resin. All the polyester resins and gelcoats I have used take the same catalyst, methyl ethyl ketone peroxide (mekp).

So I think I have an idea of what he is using.

Epoxy sucks for what he is doing. It costs too much and is harder to work with ( I have used it too). Polyester is plenty strong and will last as good as epoxy. Besides, if someone ever decides to use poly over the epoxy, it would not work.

As far as the amount of catalyst to use, that is easy. I measure catalyst in cc's. Just experiment with a smaller amounts and scale up from there.

To clean the surface be for the next layup, use 36 grit by hand, it can be worn out. Like Reese said, it will gum up anyway. This just knocks off all the stickers so they wiil not hold any air in the next layup.

:cool:

[Liqui-Fly]

Why would you want to put PE over epoxy in a trasom repair anyway? There are primers out there that allow you to do so anyway. Also I like to know wet times when I'm working; I personnaly would want to make a career out of testing cure rates. Remember this is his first time.

David

[H2Onut]

I found that roughing or scratching the surface gave me a much better bond. Now remember I was outside and lil animals and air floatsom would adhere to everything. I did not GRIND persae I just got the "shine off of it" and leveled it. Now this was epoxy, not poly and I loved the epoxy, it was far more predictable in its behavior and was always mixed at 3:1. I know the fly don't like epoxy, but for a rookie it sure made mixing a heck of alot easier. I also picked epoxy because I felt it offered superior strength and water repellent capabilities...I know this has been discussed up and down... I think you build with whatever you are most comfortable with regarless..... Fiberglass work is like Sex, the more ya do it, the better you are at it !

Remember FRESH RESIN is GOOD resin.

Time for me to go do some glassing.....hehehehe

[FCnLa]

I see no reason for career in doing this. I cannot see why it would take that long, for me anyway.

For small jobs I mix resin up in a coke can with the top cut off.

Mixing about 8 oz. of resin up in a can with 4 cc's of mekp (example).

If you wanted to mix up a quart, half gallon, or more, it is very simple if you know general math and ratio's. No one said you would waste it either. The small amount could be used.

Although mixing larger quantities would take less mekp because of more time required for the layup. A larger container will also cause more heat build up, so this needs to be considered too. As long as it kicks, it does not matter anyway on a repair. Unlike part work, that needs to be trimmed before the part goes all the way off.

I know this is his first time, that is why I am trying to help. This is why I am against epoxy. It is harder to work with, and if some goes off before he is done with the layup, it will be more costly.

Paul :)

PS. I am not into mixing unlike materials. If it's made out of poly, then use poly. If epoxy use epoxy. If epoxy is so great, then why isn't every boat builder using it?:rolleyes:

[B.Mac]

8-12cc per quart.
I'm not really a virgin but I desperately wanna do this once and right. I really appreciate everybodies input!!! Thanks guys!!!
B.MAC:D

[Techno]

I totally disagree about the quantities suggested. Don't mix up more than a few oz at a time. If you mix up that qt you'll probably end up with about 8 oz of solid plastic and a steaming melted container.
If you just scale up a small amount you better be octopus man since the heat generated by the concentrated large amount will kick off that much material very fast.
Mixing up 4 oz 8 times is much easier to deal with than mixing 32 oz in one shot.

Epoxy can be used over poly and poly over epoxy. They are both solid plastic when cured.

[B.Mac]

I hear ya. My first lay up was two layers of 1.5 oz. matt that consumed approx. 2/3 Qt. of resin @ 5cc's of MEK. I had plenty of time at the lower ratio of 8 cc's per Qt. I layed them both back to back with no break between. Then I mixed up another 1/2 Qt. at the same mix of 4 cc's per 1/2 Qt. to lay up one layer of 18oz. biaxel cloth. Had time to clean my rollers, brushes, hands and armpits.

Tomorrow I lay up 3 layers of 1.5 oz. matt and clamp my first 3/4" plywood core to the 1st inner skin layup I just described.

I stopped by Lightning Powerboats to get some materials from John (my supplier is closed for the holiday) not only did he GIVE me the stuff free Matt & biaxel but then he let me pick his brain for twenty minutes. Man, I tell you what, this guy builds a transom WOW!! I had no idea!!! Those hulls he's building are
S-O-L-I-D. I'm not doing near his layups and I'm laying this..........

1.) Inner skin .....Two 1.5 oz matt and one 18 oz. biaxel.
Let cure and scuff
2.) Three layers of 1.5 oz. matt then add first pre-resined then wetted 3/4" plywood core and clamp. Let cure and scuff
3.) Over 1st core......Two layers of 1.5 oz. matt, one layer of 18 oz. biaxel and extend the cloth 4" onto the hull. Another two layers of 1.5 oz. matt followed by another layer of 18 oz. biaxel and extend 8" onto hull. Let cure and scuff.
4.) Three more layers of 1.5 oz. matt then apply second pre-resined then wetted core over 1st core. Clamp and Screw w/ temporary 1 1/2" deck screws. Let cure, remove screws and scuff.
5.) Two more 1.5 oz. matts followed by another single 18 oz biaxel layed 12" onto hull. Two more 1.5 oz. matts and another single 18 oz. biaxel cloth laid 16" onto hull.
Let cure and scuff.
Then I begin the integrated stringer, giant knees, and additional transom layer for one piece installation.

This is about half what John's got in them Lightning hulls. I couldn't believe it until he showed me three different hulls in various stages of layup. UN- REAL.
Just call me "Itchy" MAC
B.MAC:D

[Alan Power]

A safe ratio for Polly-e is 3% mekp, mix this in a bucket and pour into a flatter or larger container this will spread the resin out and reduce exotherm in the cure/ it will last longer!
I dont ever sand/scuff/grind or anything between layers I don see the need, there is no wax additive in laminating resin unless you specified it.
Also I wouldn't laminate P/E over epoxy the bond will only be mechanical and not chemical.
If you are worried about bond between layers that are required to set before the next can be applied, use a fast set/slow cure resin-your dealer can specify a brand, tell him what your doing he will sort you out!
Nobody here is right or wrong, it's just down to personal preference - talk to the tech guys in your local suppler!:)

[Superdave]

Handy Info (http://www.fiberglast.com/charts/catalyst.php?session=ca7623b8481e6963bb7b104c340b8692)

[FCnLa]

The reason I was suggesting mixing a small amount is because I have used different resins that would go off at different times. Summer and winter resin. The winter resin would go off before you got the stirring stick out of the container in the summer!:eek:

Sounds like you have it going your way, "Itchy Mac"!:D

As far as the quantities, I have mixed as much as 3 gallons at once in a 5 gallon bucket! AND used it all before it kicked!

The quantity should coinside with the amount of glass to be laminated.

Just call me Octopussy, uh,.....octopus man!:rolleyes:

The only time I put poly over epoxy, it would not kick. It made a big mess that had to be cleaned up and redone (which cost me some time). That's why I don't mix materials.

p:)

[Rickracer]

.....is an empty antifreeze jug, with a window about the size of the label on the front cut out of it and the cap screwed on tightly. Plenty of room to saturate smaller pieces if needed, has a built-in handle, and when it has kicked, you can pop it on your knee, peel out the remnants, and reuse it a few times. :cool:

[sho305]

I used epoxy the first transom I did, but I am familiar with glass and bondo from autobody. My reason was the slight cost was worth the extra stick and water proofing in a repair. I could get around the not so adjustable kick time. I used small amounts, and it was fast/easy with the pumps to do so. I could mix more before it set. I did not sand if it was less than 24 hours old unless it was rough, per instructions. The transom I matted every 12 hours or less anyway.

I think the boat builders don't use it because of extra cost, and because they would have to change the way they do things to use it.

However, I have a 1967 glass ChrisCraft and the glass itself is fine so I am sure it works great when done properly. I just wanted the extra insurance for the little more time/cost it might take to use it.

You can get aluminum graduated paint mixing sticks at autobody supply places. If you have a straight container, they make measuring odd amounts real easy, in any amount. Or you can file notches in the wood ones and count:D