Small volume epoxy technique

[woodrat]

Hi everybody, I am gearing up for my first falcate braced guitar to be started soon and just collecting the things together. I am having a friend pick up some West Systems epoxy from Carbatec in Sydney tomorrow to save on freight (an extra $50 added to freight because they are Dangerous Goods! ) Anyway I am just getting the 500ml and 100ml size. The metered dose pumps are for the larger size apparently so I was wondering what may be the best way of metering it out accurately and with as less mess/spillage as possible. I was thinking about plastic kitchen measuring spoons. Anyone with some better method/equipment ideas.

Thanks

John

[liam_fnq]

Disposable plastic shot glasses and one of these:

http://www.ebay.com.au/itm/Digital-Prec ... 3a6de1a824

You need to do minimum 10g:2g and make the quantities pretty exact.

I keep my scale in a sandwich bag so it doesn't get crap all over it.

[jeffhigh]

Perhaps a Plastic syringe for dispensing into the cup on the scale (one for resin another for hardener)
Spoons get a bit messy and hard to control

[Dominic]

John, I got a couple of syringes, a large one for resin and a smaller one for hardener and once I use them I put a lid back on so any glue still in there is OK. You need to be pretty accurate with it and a syringe is good. You would only be mixing up a small amount and it easier to get the ratio wrong in such small batches.

Good luck with it. I wish I had more time to do this, its taken me all year to finish 6 guitars and I have plans for the next ones but I have to be patient.

Dom

[ozwood]

Hi John ,

I second Jeffs vote for a disposable Syringe, available fro the local Chemist.

Cheers,

[Mike Thomas]

I have always used scales capable of weighing to 0.1 gramme. It gives a very accurate measure for small quantities. For example, I use a small disposable plastic cup, weigh it, say 4 grammes, add 10 grammes resin and 2 grammes hardener and if it all now weighs 16 grammes, I'm spot on.

[joolstacho]

Very small resin mixes are a bit of a worry, -the less you mix, the less accurate your measurement. Epoxy resin is not gold dust so why not mix a bit more qty?
You do need to be fairly precise, but a small say, 30ml medicine type measuring cup is quite accurate enough. I'd usually mix a minimum of 30ml total (25+5). Put in the resin first and bring it up to quantity with the catalyst. Mix thoroughly, scraping the sides frequently.
I don't use syringes with epoxy because they get gummed up, are hard to clean properly and meniscus can add error. However I do use a syringe for catalyst if I'm using polyester resin where catalyst qty is around 1-2%).
BTW the pumps aren't 100% accurate either.
Make sure the resin is not cold when you mix because you'll get air bubbles through it. If you want to extend working time pour the mix into a flat tray and work out of that. Clean up with meths. Curing temp is important, I like a minimum of 30c overnight then keep it in warm room temp for a day.

[rocket]

The syringes work very well, whether you're mixing a fairly large batch or a very small one they are very accurate. I use one for the resin and one for the hardener, wash out with metho, ready for the next use!
Cheers

Rod.

[woodrat]

Thank you all for your replies. My West Systems Epoxy is coming from Sydney today via a friend of mine who dropped in and picked it up for me and saved me the freight + the $50 danger money they charge to ship it:)

I look forward to Falcating shortly!

Cheers

John

[kiwigeo]

Thank you all for your replies. My West Systems Epoxy is coming from Sydney today via a friend of mine who dropped in and picked it up for me and saved me the freight + the $50 danger money they charge to ship it:)

I look forward to Falcating shortly!

Cheers

John

For the $50 your package sits in the back of the Aussie Post contractors van with the rest of the mail.....

[Phil]

Out of interest woodrat. Why do you chose to use West Epoxy instead of old fashioned Araldite?

Seems to me that West Epoxy is formulated for industrial use, intended for extreme conditions. For your porpose Araldite would/should be adequate.

Phil.

[woodrat]

Phil, It is simply that because the West Systems is a liquid and Araldite is a Gel. One you can paint on and the other is spreadable but no where near liquid enough to wet out the CF tow in the Falcate bracing scheme.

[woodrat]

Thank you all for your replies. My West Systems Epoxy is coming from Sydney today via a friend of mine who dropped in and picked it up for me and saved me the freight + the $50 danger money they charge to ship it:)

I look forward to Falcating shortly!

Cheers

John

For the $50 your package sits in the back of the Aussie Post contractors van with the rest of the mail.....

BTW, the West Systems epoxy arrived safe and sound, delivered by a guitarist totally unqualified in Hazmat procedures. I really cant understand why they allow people to walk out of the shop with such a dangerous product.

Johnny WoodRat

[Allen]

Hi John.

I use WEST Systems all the time and I mix mine up on a very accurate digital scale that was liberated from our paint shop.

The smallest mix that I can do reliably without the resin being compromised is 10.0 grams of resin to 2.0 grams of hardener. This is the mix I use for all pore filling and laminating CF tow etc.

[woodrat]

Thanks Allen, I got it to do Falcate bracing but I will also use it for pore filling...I have tried a few things, even the egg white which was quite good. I will have another look at your toot on pore filling.

Regards

John

[Allen]

Same mix I use for the CF and balsa lattice John. It's more than you need to wet that little bit of surface out, and it's easy to think you're begin wasteful, but I've had smaller batches not want to cure properly. That's why I said that 10.0 grams resin to 2.0 of hardener is the smallest I've been able to go with reliable results. And that is measured to the tenth of a gram.

[Corky Long]

Another vote for small digital scale. Here in the states you can pick one up for less than $20 at the local Target. I use a small paper cup, zero it out, add the resin and hardener in necessary proportions by weight. Really easy, and the only waste is what stays in the cup. No need to clean or dispose of a syringe, spoon, whatever.

[luke_lee]

Hi John,
I was just wondering what hardener you got from Carbatec. I remember something in the books about a certain type of hardener for pore filling.
Did you get West System 105 resin and the 207 hardener?
Are you using the same hardener to do your carbon fibre and pore filling?

Thanks Luke

[Allen]

I use the 105 resin and 206 hardener for both bonding CF tow and rods, as well as pore filling.

I just saw that Trevor mentioned in another thread that the 207 was better for pore filling because of low amine bloom. I've never had a problem with that occurring, but have heard of others getting it. Might have to do with my tropical environment. But saying that, I'm getting low on hardener and will get some 207 to see if there is any difference for me.

[MBP]

207 if I remember correctly is a finishing epoxy not so much of a structural glue.
It doesnt yellow over time like the 205 and 206 do.
206 is the slow hardener. 209 is even slower.

A few hints (these are from using epoxy for other things not guitars so could be different)

Dont mix the epoxy in small deep containers ie shot glass. Its makes it go off a lot faster- Im not sure but I think its the SA:V.
A shallow large mix is better. Dont use glass. Mix it well but dont mix like a madman or try and do it really fast.

[woodrat]

Hi Luke, I used 206 hardener for my one and only epoxy pore fill job too and like Allen I was not aware of the blooming problem that Trevor mentioned. I will have to look into that as well.

John

[woodrat]

...I am making another falcate braced top at the moment and I remembered this thread because I had to mix small amounts of my West Systems epoxy again. Trevor recommended using syringes and drawing more than you need out and then going between graduations to be accurate which is what I did and it have been very successful. I have now found an instrument that will do all that and allow you to do very small batches too....and its very cheap.... I got a Panadol dosing syringe from a friend who has kids and always has liquid Panadol on hand for the kids. The great thing about it is that it is graduated in 1/2 ml graduations that are nicely marked. Anyway I hope that this info may help someone....

Cheers

John

[DarwinStrings]

Same here John, I use syringes and mix 3ml, that is 2.5ml and 0.5ml. I keep the last bit in the cup and without fail after 48 hours it tests as hard as the manufacturer specifies, that is that you can't scratch or dent it with a thumb nail so I am satisfied with syringes and small amounts.

Jim

[rye_bear]

+1 on weighing the epoxy

[Tod Gilding]

Same here John, I use syringes and mix 3ml, that is 2.5ml and 0.5ml. I keep the last bit in the cup and without fail after 48 hours it tests as hard as the manufacturer specifies, that is that you can't scratch or dent it with a thumb nail so I am satisfied with syringes and small amounts.

Jim

+1 I'm doing exactly the same as Jim with no probs , like Jim, I just check what is left in the cup if it's OK then I know all is good