West System Epoxy help

[icemate]

I used nothing but West Systems for 20 years. There is plenty of info available and you can also contact Gougon Bros in Ill. I think that's how to spell it. Loof on your container. They have videos and are very helpful. I never deviated from recommended mixing ratios.

[Rough Magic]

I use aluminum food service trays that are sold by catering supply companies. Cheap, flat, one shot. Keeps the mix cool, can be floated in water. Also great for disposable paint roller pans.

Try www.duckworks.com for resin.

[Mithril Bham]

I've used a lot of WS & the only time that ever happened to me is when I screwed up and mixed it wrong. Scary when the cup starts melting in your hand and smoking. Actually someone working for me mixed it 1 to 1 but I take responsibility.

[NevisDog]

Originally Posted by Thumbs Up

Lots of advice here but sorry Dave, You will have to redo it. ...

Just wanted to emphasise that point (at least two people have mentioned it). Accidentally altering the mix ratio (by even a small amount) can prevent the resin from ever reaching full strength; deliberately altering it to the extent you mention means you will have a layer of near-zero-strength resin, and everything else you attach to it will have nothing to hold onto.

Same goes for ensuring you scrape the sides of the container as you mix - anything not properly mixed in will alter the mix ratio by enough to upset the strength of the whole batch.

Working with epoxy is just about the opposite of working polyester resins, in many ways. Best to work with someone with experience first, or work on something non-critical until you get the hang of it.

[Chuck Hawley]

Originally Posted by Dave_S

I'm new to this fibreglass epoxy stuff and making a bit of a mess.

PROBLEM 1.

The instructions tell me only mix at 5-1. At that, the mixing pot gets too hot to hold, and goes off before I have put on a single coat in about 6-8 minutes. It actually melts the plastic cup.

So I used some of my creative licence and altered the mix down to 8-1 which extended the cure rate to around 10-12 minutes and not as hot but the epoxy I applied takes much longer to cure than the mix in the pot ??

PROBLEM 2

I'm assuming this is my next problem anyway.
Tomorrow I am going to mix the epoxy with a West System filler and do some filling of holes and some tidy up of the glassing I have done. All of this is on a 45° slope and I am worried it will just run. At its thickest it may be 8mm 5/16" thick.

Problem 1: Are you using 205 hardener in warm conditions? Consider using 206 or 209 hardener to slow down the cure time. Do not, under any circumstances, change the ratios. This is not like polyester with hot and cold batches. The chemistry is based on either 5:1 or 3:1 mixtures, depending on the hardener that you use. Use the mini-pumps that are called for with each of the hardeners. Period.

Problem 2: Add thickener until it stays where you put it, or put Peel Ply or some other plastic over the resin mixture to hold it in place.

Chuck Hawley

[scaredycat]

Dave,
Our Adelaide summers are way hotter than yours, and at 27 degrees, the most I would mix with slow hardened (206), would be 100g/20g. Mix well for 2 minutes (use a timer and scales set up at the mixing station). Work like the clappers to get the stuff spread out quickly, the aim being to get it out of the container asap. As the temperature of the days increase (less of a problem now its Autumn), mix less and less. On a 32 degree day, I don't mix more than 50/10 grams at a time. over 32, forget it. It will exotherm before you can get it out. Never change the ratio. It will have unexpected results and structural uncertainty like brittleness.
Hope this helps.
Greg

[billgewater]

All the advice above is good. The mixing ratios should be adhered to precisely to obtain the desired properties of strength, water proofing adhesion and clean surfaces. (That is partly why it is so expensive! It can have great properties.)
Epoxy polymerization is exothermic so care must be exercised. Use small quantities or a modified slow "hardener" component.
I use an "Alnex" product (similar to West) with a slow hardener with a 5: 1 mix ratio by volume. Usually the total mix is less than 200 ml. I actually use syringes to ensure correct ratios. I mix thoroughly then add the filler (if needed) mixing constantly. This usually is workable for over an hour. If I want a stiff, non runny mix I use Nuplex Composites ES045. It is expensive but very easy to use and has a reasonable pot life. (but hard to sand later as it contains carbosil).
Fillers.
Make sure you understand what the filler is required to do. Some just bulk the material e.g. sand, sawdust etc.
Some provide a good sanding surface e.g. Q cells, talc, and others. Some e.g. carbosil, make the mix "non runny" or "non sagging", "stiff". Ask on web sites. Pure laminating resin mixes can achieve the best "wetting out" which is essential for best adhesion and water proofing. Additives often reduce these properties.
However some advice on cooling. Just be aware that if you cool the containers or pre mixed components in a fridge, you may get water condensation on the surface when exposed to a humid environment. Test using a smooth surface container first. Water can really weaken some epoxy mixes (not all).

[Mithril Bham]

My guess is that you used too much hardener. I see no other way that the epoxy would melt the cup and smoke. I know from experience how easy it is to make simple mistakes.

[Group9]

I use the West pump kits and never have a problem.

[DerekKelsall]

Hi,
as with almost all discussions of epoxy, there is no reference to the safety issues involved and those promoting it's use are ignoring the basic safety requirements - do not inhale either fumes or dust and do not get epoxy onto skin. I have been involved with custom building for all of my career. We have this strange situation where most professional builders use polyester or vinylester resin but home builders talk of epoxy as though there is no alternative and for example, those selling boat plans recommend epoxy but do not give the warnings.
The Gougeon Boatbuilding book (1976 but still in use) says we have used epoxy for a long time with no ill effects. Jan Gougeon died after suffering respiratry problems and brother Meade died of skin cancer.
I am grateful to be able to say, I have never encourages any client to use epoxy but also to be able to say that polyester and vinylester have proven to all that is required of a resin in most boat building applications - I can point to plenty of 40+ yo old Kelsall which will be structurally sound for some decades to come.
Happy boating,
Derek.

[Terra Nova]

DK--it is well to caution safe practices, as some people can become sensitive from using epoxy. But it is disgraceful to imply that Jan and Meade died because of its use.

[jack630]

Epoxy resins are generally much safer than polyester resins. Some people might get a skin rash from exposure, so it's good to wear disposable gloves. The VOC of epoxy resins is very low especially compared to the highly volitile styrene used in polyester resins.

To thicken the epoxy resin and slow it's flow, to apply it to vertical surfaces add fumed silica, probably in the range of 2 - 5 percent by weight. Also, add some of the mineral filler that they sell, at 25 percent or more to make the epoxy like peanut butter. I forget the exact number I've used in the past but experiment with small batches until you get what you want. The added benefit of fillers is that they will slow the reaction by diluting the resin and also reduce the cost. At some point if you add too much filler it will become crumbly, but that will be obvious. Dixie cups work great for small batches.

[Dave_S]

Thanks all

It worked a treat. I bought the cheap baking trays and mixed in that. The shape on the bottom of the tray makes it hard to mix thoroughly but you just flatten it first. Mixed at 5-1 and had plenty of time. And it was hotter today.

I mixed the 411 filler, maybe a bit thicker than peanut butter but it went on and smoothed out ok.

Before I did put the filler on I removed the old epoxy layer with 40grit on and orbital sander. It sands easily. Then replaced the glass mat and put the filler on when that coat was still tacky.

I'll go back tomorrow and sand it but it looks pretty good so far, so went from pretty messy to looking pretty professional.

Thanks :-)

[Jim Cate]

Some people might get a skin rash from exposure, so it's good to wear disposable gloves.

Skin rash? Yep, but that's not all that can happen. The shipwright who built our boat (epoxy strip plank) became sensitized to the epoxy, had skin reactions but persevered (being young and driven at the time). Ended up with permanent lung damage from the fumes and totally unable to work in that material, for now even slight exposure brings on severe symptoms. (He has found that the Bote Cote line of epoxies utilize different chemistry and allow cautious usage, FWIW).

So don't underestimate the dangers... use gloves, respiratory protection if in poorly ventilated workspace and protective clothing if you are likely to get up against wet epoxy doing boat yoga.

Jim

[chris95040]

Originally Posted by Dave_S

Nothing in the instructions about that.

Nothing in the instructions about thinning the ratio, either, yet you went ahead with that experiment! In fact I'm quite sure they caution you against it for obvious reasons.

Admit it, you didn't actually read the instructions, did you?