# Epoxy Resin



## I3lazd (Dec 29, 2008)

Does anyone know of a cheap place to get epoxy resin or something else I could coat my background with. The coating doesn't have to be clear as I will be painting after coating it. any suggestions are helpful


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## Murky (Jun 13, 2007)

don't flame me If I'm wrong about something here.. but I once read that you can use fiberglass resin. and supposedly wal-mart sells it in their automotive section for doing fiberglass auto-body believe it was 9$ for a quart


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## I3lazd (Dec 29, 2008)

has anyone else on here used this?


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## xwolfiex (Feb 3, 2009)

'fiberglass resin' that is sold in home depot, walmart, etc., is polyester resin, it is* not* waterproof, only very water resistant. when it is used on boats and other marine uses, it is itself coated with gel-coat or a different sealer


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## CHBGator (Oct 5, 2006)

xwolfiex said:


> 'fiberglass resin' that is sold in home depot, walmart, etc., is polyester resin, it is* not* waterproof, only very water resistant. when it is used on boats and other marine uses, it is itself coated with gel-coat or a different sealer


Hes right. There are 2 types of resin and the automotive stuff will not work you *need* Marine Grade resin.


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## newfisher (Dec 20, 2008)

There are three main types of resins used for fibreglass work: polyester, vinylester, and epoxy.

Polyester remains porous, thus letting water in (i.e. cause of blistering on boats). It will dissolve most insulating foams (the stuff most people use to build backgrounds), smells like **** until cured, and makes a very poor adhesive. There are two general grades: laminating, and finishing. One will remain "sticky", and I wouldn't use it near fish.

Most epoxy, once properly cured, is waterproof, non-toxic (but don't try to eat it!), tougher and more flexible than polyester resin, is a great adhesive, and generally produces very little odour while curing. When applying several layers of epoxy, try to go "wet" on "wet" (apply new stuff before first layer cures). Otherwise, anime blush (a waxy film) may form on the surface of cured epoxy, which needs to be washed off (water does the trick). Just don't get epoxy on yourself, but if you do, wipe it clean with rags and use soap and water to wash off (better yet, wear gloves!). Avoid using solvent to wash epoxy off skin ... solvents will cause epoxy to penetrate into skin pores. Epoxy can be coloured using most dry pigments (Lee Valley Tools is one source). For applications beyond glass laminating, it is usually best to add thickeners to epoxy (glass bubbles, carbosil ... don't breath these unless you want silicosis).

When working epoxy, mix only small batches, as large batches will quickly heat in the pot (too hot to hold) and flash (cure within seconds). The vapours produced from flashing epoxy ARE toxic ... be prepared to pitch the flashing pot out a window. However, when spread thin, epoxy will not flash, and depending on the hardener used, will remain workable for quite some time.

Vinyester has characteristics and costs that are about mid-way between those of polyester resin and epoxy. However, I've only seen it available in 45+ gallon quantities ... a bit more than you would need for a background!!

An inexpensive source for epoxy is Raka Inc. in Florida (www.raka.com). They do their own mixes from bulk stock, thus obtaining various characteristics and hardening rates. I've used about 60 gallons of their "regular" stuff on boating projects with great success. I've also used it on my background and it's been holding very well now for four years.

There are a couple of other sources in the US, but I've not used them, and I can't remember their names. Their prices are in line with Raka prices.

I built my background to represent dipping and fractured bedded sandstone and shale (using insulation foam sheets of different thickness to simulate different thickness beds), with space behind for filter intake and pump for UGJ, and a screened intake to the back side of the background. I used a heat gun (type used for stripping paint ... way safer that using a propane torch!!) to texture the background and "weather" the sandstone. I covered the back (straight, smooth surfaces, except for channel ways to filter intake and pump) in fibreglass and epoxy for added strength (to avoid failure where the background is siliconed to the aquarium), but simply brushed thickened, coloured (different shades for sandstone vs. shale) epoxy onto the front, then sprinkled sand (different colours and size depending on type of rock being simulated) onto the wet epoxy and let cure. Then brushed off excess sand, and put the garden hose to the background to wash off any anime blush possibly on it before installing in the aquarium.

Hope this helps.


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## coldfusionpower (Oct 9, 2008)

newfisher, how about those fibreglass resin for water storage tank ? can i use those for the inside of plywood tank without the fibreglass mat ?


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## I3lazd (Dec 29, 2008)

you want to use the cloth is you are sealing a tank it will add durability to the tank and will ultimately last longer. I have been getting my resin from U.S. Composites but it is just so expensive I dont want to buy that just for a diy background.


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## PsYcHoTiC_MaDmAn (Dec 26, 2005)

to my thread.

what do you think about using it to seal the base of the tank??

would I need cloth/matting in there, or just resin (would it work??)


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## newfisher (Dec 20, 2008)

Most of my experience with epoxy has been doing structural foam/glass/resin composites for hovercraft hulls, glass/resin air handling ducts, laminating propellers, making water holding tanks, fuels tanks, etc. I've never built a plywood aquarium. That said, while straight epoxy will seal the ply, it will not provide any significant additional strength. It's the combination of glass and resin that gives composites their strength. If I were building a ply aquarium, I would use glass over the interior, particularly at the corners. Note that when doing corners, chamfer them using a resin/micro-balloon (or similar filler) mix, otherwise the glass cloth will not adhere to the corner (fibreglass does not like going around sharp corners, interior or exterior).

It's best to not use mat with epoxy. Mat is designed for polyester resin, which will dissolve the binding that holds the mat together. Epoxy will not dissolve the binding, resulting more than likely in air bubbles getting trapped in the work. Mat is usually used in addition to cloth to obtain a smoother surface under gel coats in fabrications built using moulds (cloth texture would otherwise telegraph through). There is otherwise very little benefit to using mat. It has only a fraction of the strength of woven or non-woven fibreglass, so dollar for dollar, you're probably better off using glass cloth only inside an aquarium, regardless of the type of resin used. A single layer of ~12 oz simple weave cloth, with about 2 inch overlap at the corners (2 to 3 layers thick at corners) would give you a plywood tank that would require a chain saw to take apart. The tank could be finished with pigmented epoxy, but an epoxy paint or similar would probably give a better finish, particularly if UV light (direct sun) is likely to contact the raw epoxy (UV light can significantly degrade epoxy).


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## I3lazd (Dec 29, 2008)

I am using fiberglass and have laid 4 layers of 6 oz with each layer overlapping the corners. I layed the first 3 clear and used the dye from the epoxy maker for final layer looks amazing here is a shot.








I am laying the floor now and it is a pain in the a**.


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## PromptCritical (Feb 19, 2009)

First off, I'm new around here. I've been browsing around for a while...lots of good information from you all. My question is, does epoxy resin melt styrofoam if styrofoam is used as a form?


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## I3lazd (Dec 29, 2008)

It will slightly but you can use the foam as a mold then take out the foam after resin sets.


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## PromptCritical (Feb 19, 2009)

Thanks...That's what I wanted to do...remove the styrofoam.


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## Hoosier Tank (May 8, 2007)

PromptCritical said:


> First off, I'm new around here. I've been browsing around for a while...lots of good information from you all. My question is, does epoxy resin melt styrofoam if styrofoam is used as a form?


As stated, epoxy resin hardly distorts the foam... but the more common Polyester resin melts styrofoam on contact.


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## newfisher (Dec 20, 2008)

Epoxy should not dissolve foam at all, unless the formulator has added solvent to modify its viscosity. Solvent evaporation during curing can cause some dimensional change, result in a weaker cured product (perhaps not too critical for backgrounds), and (I'm not totally certain about this) result in longer-term slow release of trapped solvent (perhaps not so good for backgrounds). Good quality epoxy should be 100% solids ... no solvents.

Epoxy will bind to the foam form, such that a "skin" of foam will remain on the epoxy after form removal. This may not be an issue in many cases, but where it is (for appearance or chemical reasons, eg. fuel tanks), one solution is to apply a layer of plain packing tape (the ~2" wide plastic stuff) to the foam, then epoxy over that. Epoxy will not stick to the tape, so it and the foam will come off clean, leaving a smooth finish (but with tape impressions).


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## I3lazd (Dec 29, 2008)

it does too melt it, when you add the hardner to the resin it heats up if you have ever used before.


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## PromptCritical (Feb 19, 2009)

Thanks for the replies. Packing tape seems like it would be a good idea. I think I may give this a try. Thanks again.


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## newfisher (Dec 20, 2008)

I3lazd said:


> it does too melt it, when you add the hardner to the resin it heats up if you have ever used before.


I've only used 80 to 90 gallons, so my experience with epoxy is quite limited.

The hardening process is exothermic (releases heat), but in normal use (spread thin), heat is released such that curing epoxy may feel only slightly warm at best. When in a mixing pot, the heat produced from curing will move the curing process further, which in turn causes more heat, etc., until the mix flashes (goes to gel). By then the pot is probably too hot to hold.

If it's hot enough to melt foam, then the epoxy is probably releasing significant amounts of fumes and you have a much bigger problem on your hands than melting foam! Use a slower hardener. Mix smaller batches. Use up the mix more quickly. Cool parts A and B before mixing. Cool the room down. Dump the mix into a larger pan to allow the epoxy to spread to a thin layer. Do whatever it takes to avoid it going exothermic!

If epoxy does go exothermic, remove the pot from the workshop immediately. Immerse the pot in water to cool it and reduce the volume of fumes produced, or better yet, open a window and pitch the pot into a snow bank if there's snow where you live. The fumes are noxious and should not be inhaled.

It's not likely to self-ignite, but should it go to flame for some reason, use a CO2 or dry powder extinguisher. Don't use a full water jet as it will only spread the flame!

As I said, epoxy should not dissolve, or melt, foam.


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## JALOOS (Sep 6, 2008)

I am going with newfisher on this one. I spray epoxy everyday on structural steel. The exothermic reaction is indead acurate and I can atest to that for sure. That being said most hardeners also contain MEK (methyl ethyl ketone) which in iteslf will actuall bond plexiglass (I have used it to do so) and is what will more than likely melt the foam. Most epoxies are anywhere from 80% solids and up. 100% is very hard and will have severe exothermic reactions in quantity (had a 5 gallon mix cook off once at 298 degrees F) and even small amounts in pot will get hot fast. Best case for epoxy on foam is to spray light coats with several fog coats to start off with so the foam isnt reacted with as much. Recoat as manufacturers directions as the amine does posses a problem if you leave it too long, more common on the higher solids epoxies. Most will have recoat windows of between a min of 4 hrs and a max of 24 to 48 hours.


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## newfisher (Dec 20, 2008)

There are several different (albeit subtle) variances in epoxy formulations, each suited to a specific range of purposes (laminating, coatings, general adhesion, encapsulation, etc.). That said, while MEK is used in some hardeners, I would disagree with you when you say it is in most epoxy hardeners.

MEK, or other solvents, are generally not used in epoxy designed for marine, aircraft, or general use. Solvents are used to thin epoxy, but can have a significant impact on finished product ... see http://www.seqair.com/skunkworks/Glues/ ... nning.html ... this is a West Systems-centred article, but is applies to most other marine and aircraft-grade applications.

I am guessing that the MEK in the hardener you use serves to reduce product viscosity for spraying. I am guessing also that you use MEK for clean-up? (otherwise you'd be going through spray equipment at a scary rate) and that you wear something just short of a space suit when spraying? (breathing in catalysed overspray is never good).

MEK is used as epoxy solvent because: a) it is very effective, and b) it is less flammable than acetone or many other equally effective solvents. However, MEK is not nice stuff to work with (but then, nor are ost of the other solvents typically used with epoxy and other resins). MEK will penetrate latex gloves and be adsorbed into skin and the bloodstream. When mixed with epoxy it will cause epoxy in contact with skin to penetrate much more deeply. It will also cause more epoxy fumes to be released. MEK will have little if any effect on the structural (PE) foams that are used in marine or aircraft fabrication (Klegicell, Divinicell, Core-cell, etc.). However, in keeping closer to the original intent of this thread, MEK will melt polystyrene foam (the white beaded foam and the pink or blue foams used for insulation).

I agree with you when you suggest spraying thins coats of MEK-thinned epoxy on PS foam. But with high solids epoxy that is not necessary. Wet on wet applications are always better (you get a chemical bond and there's no anime blush yet). Second coats over cured epoxy (particularly high solids stuff and in humid conditions) should be preceded by soap and water wash with a stiff brush to remove anime blush (not necessary if using peal-ply), then a quick sanding to increase mechanical bond (chemical bond no longer possible with cured epoxy). Do remove anime blush first, as sanding will only spread it around ... new epoxy will no bond well if there is anime blush (but probably not critical for an aquarium background).

As an aside ... a 5 gallon mix flashing ... YIKES!!


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## JALOOS (Sep 6, 2008)

newfisher said:


> As an aside ... a 5 gallon mix flashing ... YIKES!!


Yes the MEK is for thinning for spray purposes. And yes a 5 gallon flash as it only has a pot life of 20 minutes from mix to spray to cleanup (unthinned less if thinned), 100% solids 45 to 75 mil thick in one pass. If your out of that window you and your airless are done for.

Several epoxies are also full of toluenes, zylenes ,benzyenes and other fun chemicals thats will also eat polystyrene foam. Unless you are using a 100% solids epoxy there is going to be solvents that will harm the foam.


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## newfisher (Dec 20, 2008)

--snip-- Unless you are using a 100% solids epoxy there is going to be solvents that will harm the foam. --snip--

I agree 100%

-- snip -- 5 gallon flash as it only has a pot life of 20 minutes --snip--

A 20 minute pot life on 5 gallons suggest that you must be using a very slow hardener to boot. You guys must spray fast!

For fibreglass laminating, I typically mix up to 6 oz batches for small items or where I need to add fillers and/or spread epoxy with a brush, up to 32 oz batches (I use a 2:1 part A:B formulation of 100% solids epoxy) for large pieces where I can quickly dump the mix onto the work and spread it with a squeegee (most of my work involves epoxy/glass/structural-foam construction, with some form work thrown in from time to time). Working times are 20 to 30 minutes for the first example (less if the room is too warm), up to 1 hour (but that's pushing it) for the second example. What size batches to you typically mix, to cover what sorts of surface area?

I ask this because it sounds like you and I work at different ends or scales of epoxy application regimes, I've never needed to mix a 5 gallon batch and I'm curious, and this dialogue might help "listeners" who don't have any experience with epoxy to learn what sizes of mixes to use.


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## JALOOS (Sep 6, 2008)

Depends on what I am spraying and with what. I use a 59 to 1 airless for the 100% solids and that is generally a tank liner but used on some high corosive environments. That has to be mixed in a 5 gallon no exceptions and there are very very stringent requirements temp, humidity and product life (no more than 3 months old). I actually have used a cooling bucket to keep the temp down while spraying the stuff and a spotter for time and to swap the solvent to the airless at the right time whether I am done spraying or not.

I also use a convention pressure pot and gun for other surfaces. These I will mix a gallon at a time and are usually 80% solids. They are also used for very high corrosive environments. I also spray extreme high heat, 2 part polyeurethanes, high zinc epoxy coatings. Everything I paint with is a 2 and sometimes 3 component coatings from 8 mill to 45 mil dry film thickness on near white blasted steel, aluminum, galvanized or stainless.


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## auratum (Jul 6, 2006)

newfisher said:


> Do remove anime blush first, as sanding will only spread it around ... new epoxy will no bond well if there is anime blush (but probably not critical for an aquarium background).


newfisher,

I appreciate you sharing your expertise here. One small correction - I believe you are refering to "Amine" blush rather than "Anime".

I have not yet worked with any epoxy short of the double tube of epoxy glue, but I understand there are low/no blush epoxies available. Sounds like they would be worth their cost for these types of projects...



I3lazd said:


> I am using fiberglass and have laid 4 layers of 6 oz with each layer overlapping the corners. I layed the first 3 clear and used the dye from the epoxy maker for final layer looks amazing here is a shot.
> 
> I am laying the floor now and it is a pain in the a**.


I3lazd,

Why did you decide to go with 4 layers of 6 oz glass? Seems extreme. It also seems odd that you did not overlap the bottom with the sides during your 4 layer process? How many total coats of epoxy did you end up applying to totaling cover the 4 layers of glass cloth? How many gallons of resin/hardener will you end up using? What brand of resin did you end up using?

I am asking lots of questions as I am planning a smaller build and planning out the construction.

Thanks,
Patrick


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## newfisher (Dec 20, 2008)

Auratum,

Thanks for the correction. I'm a bit dyslexic I guess ... get my m's and n's confused, type d's instead of g's, etc. Spell checkers catch most, but not all (


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## auratum (Jul 6, 2006)

newfisher said:


> Thanks for the correction. I'm a bit dyslexic I guess ... get my m's and n's confused, type d's instead of g's, etc. Spell checkers catch most, but not all (


No worries - I find myself being a bit lysdexic at times as well :thumb:


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## I3lazd (Dec 29, 2008)

Quote "I3lazd,

Why did you decide to go with 4 layers of 6 oz glass? Seems extreme. It also seems odd that you did not overlap the bottom with the sides during your 4 layer process? How many total coats of epoxy did you end up applying to totaling cover the 4 layers of glass cloth? How many gallons of resin/hardener will you end up using? What brand of resin did you end up using?

I am asking lots of questions as I am planning a smaller build and planning out the construction.

Thanks,
Patrick"

It may sound extreme but it is 700 gal. of water I dont want it to leak. I did one coat of epoxy per layer of cloth. I did lay an initial layer of resin before any cloth. I am using about 5 gallons of resin and hardner. I used U.S. Composites 635 thin 3-1. U.S. Composites has the best prices and when you order make sure you order your dye with the order.


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## niccomau (Oct 14, 2008)

you guys are very informative! Thanks!


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