Newbie to Epoxy

[PGplastic]

Hi all.

I have just about completed my sanding part of my blister repair project. Ordered the basics for West Epoxy: resin, 206 hardener, various fillers for the future, and barrier additive. Also ordered mixing sticks, roller covers, but was unable to order roller frames, stiff brushes, roller pans, and mixing pots. I have an old roller frame used for interior paint. Stiff paint brushes I can find. What do you recomend for rolling pans, metal or plastic or throw away plastic liners? We have a ton of old Dannon yogurt containers (32 oz). Is that type of plastic OK to use when mixing epoxy or do I need to use a specific type of plastic container? Any other tools, tips or tricks I need to know before I begin?

[Figment]

Disposable plastic tray liners are absolutely the way to go. In a pinch, I've used saran wrap.

Those 32oz yogurt tubs will make fine mixing pots, but you'll still want something smaller for measuring the raw components.

[Tim]

You didn't mention whether you also ordered the West System "Mini-Pumps" for your resin and hardener. If you use these pumps, you can easily mix in any container, but the pumps are only good for small batches since they are very, very slow. You'll drive yourself nuts trying to use these for anything but the smallest batches.

For measuring larger batches, I recommend plastic containers that have measurements marked on the sides. You can find these anywhere, usually in the paint section. This makes measuring any amount of epoxy easy and clearly visual. Accurate measurement of the epoxy components is an absolute must. The mix will tolerate the usual small inaccuracies that are inherent with this sort of measuring, but must be otherwise as accurate as possible. Mini pumps (for West System) or decent marked containers are required.

[cliffg]

I have several metal paint pots and use them to mix epoxy. I have the pumps to dispense the epoxy and hardener. Since these pots are a little bigger and provide a broader surface I find the epoxy doesn't kick as quickly as n smaller containers. When finished I just pour some acetone into the pot and clean it up with paper towels. I like these pots because they are rigid, have a handle and are big enough that you can mix the filler without getting it all over the place. They are easy to carry around and are stable and don't tip over easily.

I agree with the roller pan liners though, it would take too much acetone to clean them up.

[CharlieJ]

So don't clean them. Just let the epoxy cure inside. It'll gradually fill up the little waffles in the bottom. When it gets too thick for ya, just chunk the liner and start a new one. I had one that got to be 1/2 inch thick on the bottom. My wife called me a cheapskate for not throwing it away *grin*

Washed out tin cans make excellent containers also.

Also- I use the three inch frames and cut my roller to fit using the band saw. A whole roller now feels way wasteful.

[MikeD]

FWIW, go with the pumps. I thought I'd use the "measure" method and skip on the pumps. The 5 gallon resin bottle pours OK - the hardener in the can does not! For bigger batches, you could pour the resin and just pump the right measurement of hardener.

Oh, also, don't mix too big of a batch. When the pot "kicks", it gets hot, then unusable. A bigger batch gets hotter - and latex glove DO NOT insulate! Don't ask.

BTW, great tips on the buckets guys! I didn't realize you could reuse them. I figured "blush" or contaminents or something would muck things up. I must have wasted at least 2.50 in plastic buckets this weekend.

[JetStream]

This is probably the wrong place to stick this post but anyway ......
I recently designed a special ratiometric scale for mixing epoxy. It is designed to compensate for the difference in density between resin and hardener and allow you to mix whatever quantity you want up to about a quart (2 pounds) at a time. It bypasses the inaccuracies of the mixing container and will tare out as much as a metal 1 pound coffee can. I originally thought it might be a nice product to market for boat building shops but I'm not sure the market is there. The ratiometric weights were split so that you could use 1/2 fast and 1/2 slow hardener to get a medium mix, or you could use them together for a slow or fast mix. Here is a pretty self explanatory picture:

If you folks think that I'm wrong about the market, maybe I'll reconsider.

[Tim]

For bigger batches, you could pour the resin and just pump the right measurement of hardener.

I would recommend either using the pumps, or not using them. For most hobby-sized batches, the pumps are the safest bet, but when you get into the amounts needed for a recore, for example, it's best to just pour the resin and hardener into graduated containers for measuring--or at least I think so! It takes a while to fill a decent-sized pot using the pumps, as you only get an ounce or so per pump.

When measuring bulk amounts, it's best to pour your resin into one container first, hardener into another, and then mix the two when you are confident in the amounts. If you happen to overpour one or the other, no harm is done. It also happens to be easier to precisely meter the amounts when pouring out of a smaller container than the glugging and heavy bulk containers, so it's perfectly fair to, say, transfer the resin and hardener you anticipate needing for a job into a couple buckets or pails or whatever, and then pouring into calibrated containers from there for a precise mix.

BTW, once the mix starts getting hot, it must be discarded at once. You can't risk continuing to use a mixture that is beginning to cure; this can really make a mess of your job. With experience, it's easy to tell when a pot of epoxy is starting to kick: a mix including fillers will tend to get looser and more "watery", and a pure resin/hardener mix will get thicker and more gel-like.

If you want to extend pot life, pour the mix into a wide container of some sort--like a roller pan, or a casserole dish. Smaller buckets and pots encourage the exothermic reaction and will get hot more quickly. But you must always work quickly, regardless.

[PGplastic]

Thanks for the information.

Yes, I did order the metering pumps. The resin and hardener are group size B. I anticipate the mixed (unthickened) epoxy to be somewhat watery, based on the viscosity information I read. Maybe, it's more like warm syrup at this stage?

I plan to experiment on plywood (even though it's porous) prior to trying it on the boat. That way I can tell what kind of coverage I'll get and how fast I must work before it kicks. Since it's a small boat, and I'm starting with the keel, I'll be working in small batches first. Actually, I'll fill and fair first, then cover the keel, working my way up to the topsides. My reasoning is this; she's on homemade boat stands right now, not resting on the keel. Once the keel is completed, I'll let her down and finish the topsides.

Coverage is my biggest unknown right now. I read a gallon will cover 400-500 square feet, but of course, I won't mix that much at once. I figure I'll mix 16 oz and see what kind of coverage I get. Then work from there. Unless you good folks know already. :)

The pan liners are a good idea. Glad the Yogurt containers are OK, too. I guess I was concerned about a reaction between the plastic and the mixture and any contamination from a possible reaction. Sounds like there won't be.

Last question for now (other than the coverage issue): If the pot life of #206 is 20-25 min at 72 deg F, how much shorter is the time I have at 85-90 deg F?

Thanks,

Paul

[CharlieJ]

quite a bit shorter.

In temps like that I usually never mix more than about a pint at a time. I have glassed in temps of over 100 but you REALLY have to move or you'll lose even a small batch. One thing to beware of in higher temps. the resin left in the container will begin to cure after about the second batch. Have several containers. Use one for maybe 2 batches, 3 at the most. Then set that one aside and let it cure. Start the next batch with a fresh container.

I've used empty washed out tin cans, butter tubs, yogurt containers ( OFTEN- I save them just for that) and the containers that icing comes in when you bake a cake.

One method I use is to measure with a stick. Meade Gougeon showed me the method. You MUST, repeat MUST have straight sided containers for this.

Mark a stick in the correct increments for the resin. Let's use 5 - 1. Mark the stick 5 increments from the bottom. Then go up one more increment and draw another line. Just for example- mark a line at 5/8st, then another at 3/4 (6/8ths) up. Or for larger batches you could use 2 1/2 inch and 3 inch. Or 5 and 6 inches if you are feeling speedy ( and lucky). You can control the size of the batch also by the size of the container. Obviosly 2 1/2 inches of resin is a lot more in a large juice can than in a V-8 can.

Now pour resin to the first line. If you have a large job, you can pre-pour into 3, 4, 6 whatever number of containers you think you'll need, up to the first mark. Then stick the stick back into the container and pour hardener to the second mark. Of course if you pre-pour, you would do all the resin first so you wouldn't get hardener in there til you were ready. Stir and go. Sure speeds things up when doing a large job by yourself because your resin is all pre measured. I glassed the bottom and topsides of a 22 footer by myself in 95- 100 degrees that way.

Of course for a 2 - 1 ratio then measure up 2 increments then one more for the hardener.

For very small batches ( VERY small) I use the inner part of one of the caps on a can of spray paint. It's pretty tiny and straight sided. I have used a stick marked in 16ths- 5 / 16ths for the resin and one more (6/16ths) for the hardener. Gives me a little less than a tablespoon full. Or about 1/2 a pump. Gotta be careful pouring but it works well.

Other than the above, I use pumps exclusively and have since 1976 with no difficulties. I do get new pumps each time I start a new boat however.

One other tip on extending the resin- put your resin in a paint tray ( liner would do) then set that tray inside another filled with crushed ice. The crushed ice will keep the resin cool and really go a long way towards extending the pot life. I used that when rolling fill coats onto glass work on a trimaran outer hulls in Florida in July with no shade - 32 foot long hulls

STILL had to hustle *grin*

Also- be aware - when a container of resin that is kicking begins to smoke- its no joke. A friend of mine burned his boat up with a container of resin- it got hot and set a roll of paper towels ablaze- total loss of a Seaward 25.

[Tim]

If the pot life of #206 is 20-25 min at 72 deg F, how much shorter is the time I have at 85-90 deg F?

Note that "pot" life doesn't really mean the length of time that epoxy will last in what we might typically call a pot--one of these plastic containers, for example. A narrow, deep container (relatively speaking) will substantially shorten this estimated life to begin with; you'll never get 25 minutes' working time from a half-full yogurt container at 72?. The estimated "pot life", or working time, is generated based on some specific set of situations and standards that are probably more optimistic than real-world conditions.

I wouldn't mix any more than you can use within 5-10 minutes or so at that temperature. It's better to make numerous small batches than to waste large amounts when it kicks off too soon.

A while ago, I made a substantial investment in the West System gear pump for dispensing resin and hardener. There's no looking back. It takes all the effort and thought out of mixing resin: just turn the crank and go. It's just too bad they had to price this device so far out of reach for a typical project boat owner.

[Tim]

This is probably the wrong place to stick this post but anyway ......
I recently designed a special ratiometric scale for mixing epoxy. It is designed to compensate for the difference in density between resin and hardener and allow you to mix whatever quantity you want up to about a quart (2 pounds) at a time. It bypasses the inaccuracies of the mixing container and will tare out as much as a metal 1 pound coffee can. I originally thought it might be a nice product to market for boat building shops but I'm not sure the market is there. The ratiometric weights were split so that you could use 1/2 fast and 1/2 slow hardener to get a medium mix, or you could use them together for a slow or fast mix.

That's a handsome device, Bruce. I admire your conception and workmanship.

There's probably a market for such a thing somewhere. At most boatyards and builders that I am familiar with, however, I'd have to say that it wouldn't be the measuring device of choice.

What would happen over time, for example, as parts of the unit get covered with excess resin and hardener (which always happens in practice)? Wouldn't this eventually throw off the calibrated weights? People often mix resin batches with sticky gloves, and the materials themselves are messy to pour in many cases. Cleaning the parts of the scale each time isn't a realistically practical solution, however ideal it might be.

The ideal mixing device for any shop is quick, easy to use, accurate, and generally maintenance free--and affordable. Guaranteeing the accuracy over time is the most challenging aspect of any dispensing equipment. I assume that's why the West System gear pump, which meets all of the above criteria except affordability, is so expensive.

I'm not an inventor and don't have any great ideas, but I do know that when I want resin, I want it now, I want it easily, and I want it accurate without a lot of fussing around. This is particularly true when mixing multiple and successive batches in a one-man shop, where time is important.

For small jobs and where a slower pace is possible, a highly accurate device like the scale might have applicability. But even though the potential accuracy is very high, it still very much depends on the user to ensure that the scale is perfectly balanced when the components are added; this necessary attention to detail, when used to mix in calibrated pots, will acheive a successful and accurate mix as well, so for most practical purposes this would be easier and quicker than the scale.

For research or more scientific uses, where documentation of mix accuracy might be critical to the results, a scale like yours would certainly be invaluable.

[grampianman]

Disclaimer: With this post, I'm not trying to imply I'm in the same league as Tim and friends, I'm not in the same universe!

To throw in my two cents, I use the gallon and quart sizes of West resin and hardener, with the metering pumps, also from West.
I used Dixie (or similar) cups - 10 oz size, for my small batches.
I cut the top and front of plastic gallon-size milk jugs off, leaving the handle in place, along with about half of the bottom. (In terms of amounts, the most 'pumps' I mixed into this container were about 20.) I never took the chance of mixing a second or third batch in a 'used' container, we go through so many gallon jugs of milk in my household, I had/have a ready supply. The Dixie cups are thrown out after each use, the gallon jugs and any other plastic containers (yoghurt, etc.) are set aside to harden after which I could peel/pull the set epoxy out. My stir sticks I always washed off with acetone and wiped dry. Working here in South Florida, I have encountered too many batches, even when small, going off at too quick a pace. The worst time was when I didn't realise I had set the epoxy container down in sunshine as I was working in shade at the time!
Oh, yes, lots of gloves.

Cheers,
Ian

[Capn_Tom]

When outside temps are high or you want to extend your open time, nest your container in a container of ice. It will absorb the heat from the exotherm and increase pot life considerably.

[bhartley]

I use milk jugs also to mix my small batches of epoxy -- both gallon and quarts. For fairing, I cut the gallon jug top to bottom and have a nice wide "trough" to mix the filler.

Although we use a reasonable amount of milk, I reused my milk jugs many times by leaving the mixing stick (disposable wooden stick) in the leftover epoxy in the bottom of the container. Even a thin film was enough. Once the epoxy kicked, I used the stick to pull out the entire cured epoxy in one fell swoop. Epoxy doesn't stick to HDPE. The sides are quite flexible to get off anything that doesn't come off with the original mass. Clean as a whistle. Quick acetone rinse to remove any gug and back to work.

Granted my boat may disintegrate once she hits the water... but the epoxy seems pretty darn solid.

[PGplastic]

Thanks for the tips. Good ideas for efficient work.

[MikeD]

Probably a real obvious question, but what the heck: what do you do with your reusable tools (rollers, trowels, squeegies, etc.) after working with them in epoxy. Wipe them clean with acetone before the stuff sets?

[Tim]

Yes. Or soak them in a bucket of acetone. Put a cover over the bucket to prevent rapid evaporation of the acetone, though.

I bought a small parts washer and use that as an acetone tank. I removed the pump and spigot because it was not rated for flammable solvents, but I really only needed the tank.

[JetStream]

Well Tim, I think I got my answer on the epoxy scale. You were the only one to reply - probably out of your kindness (and with a very well thought out response). I had already figured that the market was iffy, even though MAS Epoxies really liked the product. I guess I might have a winner if I could replace the stupid push pumps with a very inexpensive crank metering pump. I always hated it when I'd be half way through pouring a batch with the push pumps and one of them would "burp" so you really didn't know how much material had come out.

[Figment]

The balance scale method of proportioning the resin components works very well if the resin is simply poured instead of pumped. The plastic spigots on the 5gallon and 2.5gallon system three jugs were the handiest thing ever. I had a clumsy scale set up (only for a short while due to space constraints) during my deck recore, and was happy with it. It does become a big gooey mess after a while, though, so either it needs to be VERY easy to clean, or it needs to be so cheap that it can be considered somewhat disposable.

[PGplastic]

OK. Here is a link to photos of work completed thus far. I think I'm starting to scare myself. :)

Pictures will speak for themselves.

Have had a fan blowing at the hull. Tonight it's blowing through the companionway and out two access ports. Trying to dry the nether regions of the interior, too. Just in case.

PICS[/url]

[PGplastic]

Quick update.

I have been playing with the test panel of plywood and small batches of epoxy. Tried it neat, with colloidal silica, and 410 fairing. Am I glad I have!?

Neat epoxy is pretty easy to work with. Bonded a block of wood to the plywood with the c. silica. Worked nicely first try. Fairing 410 is a little different. My first batch sagged pretty badly even though I thought it was peanut butter consistancy. Second try was more like slightly moist clay (if you've working in pottery). Very dry. But, upon spreading, it smoothed out fairly well. Looked like cake icing with a very slight texture.

Two lessons learned with the fairing. Make sure the neat epoxy is gelled, at least. That is, tacky. Otherwise, the fairing will slip. And, "dry" peanut butter may be a better consistancy.

Is that about right for your experience? I appreciate your input. Thanks in advance.

[CharlieJ]

you can go with a slightly thinner filleting blend - peanut butter consistency-if you add just a tad of silica in there too. Doesn't take much but goes along way towards stopping sagging.

The WEST wood flour ( filleting blend) has silica added when you get it, so it shouldn't need much if any at all.

[Tim]

Agreed. Your fairing mixes will be entirely unsatisfactory without the addition of some silica to the fairing filler. It really pulls the mix together and helps you get a workable consistency. Otherwise, the material will sag and be miserable to work with.

Your second attempt is typical of batches made with only the fairing material, and no silica. Add enough of the fairing filler and you will eventually get a pretty thick mixture, but it's not a very good consistency--and uses far more material than necessary. Your fairing compound should never resemble clay--that's far too thick and dense, and it would never work over a larger application area like your hull.

When mixing, first mix the resin and hardener well, then add the fairing filler as needed. There is no hard and fast rule for how much, but in general you're looking to partially thicken the mixture without it becoming gritty or dusty. Try some small batches, mixing in the fairing filler only until the mixture is somewhat thick, but by no means spreadable. Then add in some silica. Adding some silica at this point will bring it together and thicken it nicely. Add a little at a time in this application, as it's also easy to overthicken. Experience will quickly show you how this works. Silica is a pain to mix in because it's so lightweight, but you'll get it.

Note that 410 (the "microlight" compound") is not for use in high heat areas, such as decks or beneath dark paint. It can soften. A better all-around fairing filler is 407, or phenolic microballoons--the reddish-purple stuff.

[CharlieJ]

Tim says- "Silica is a pain to mix in because it's so lightweight, but you'll get it."

OH boy is THAT an understatement *grin* The stuff can go all over the place. Never try to mix it in any kind of breezy place either- you'll wind up with nothing in the can.

Bad stuff to be breathing too- remember- Silicosis can be the result. Doubtful an amateur working on one boat would get enough exposure, but Tim or I certainly could. But why take chances- wear a mask when using it. Micro ballons also.

[Tim]

Bad stuff to be breathing too- remember- Silicosis can be the result.

Wow--there's actually a condition based on ingestion of silica? I didn't know that. I guess it's logical enough. I just figured it would cause general respiratory harm.

I did know it was nasty, though. It's very easy to breathe in (almost impossible to avoid), unless wearing a mask. I hate the stuff!

[CharlieJ]

Silicosis is a lung disease- caused by breathing the stuff. Just like Asbestosis.

[PGplastic]

Thank you for the pointers. I will continue to practice (safely) as I finish the sanding and drying of the hull. My day job is getting in the way of my projects. :)

[keelbolts]

Keep it off your skin. Do not breathe the dust when sanding. I know of two people who are sensitized to epoxy. One ran a boat yard & had to find a new way to make a living. "They" are not kidding when they warn you to treat this stuff w/ respect. Finally, here's a really nifty trick:
To clean up epoxy, before it kicks, nothing works better than plain old distilled white vinegar. Forget acetone and other liver eating chemicals - white vinegar. Finally, something nontoxic.