bigwow
Well-Known Member
I used to mix a bucketful with polyester then just catalyse enough for each job.
Using epoxy mini pumps.
- Thread starter FairweatherDave
- Start date
I used to mix a bucketful with polyester then just catalyse enough for each job.
DownWest
Well-Known Member
More or less what you buy with car body filler.
DownWest
Well-Known Member
Chatting to the guys at SP, quite a few yrs ago, They said to mix the resin for two minutes and be careful to scrape the the sides of the cup as you do it. THEN mix the fillers. Much more difficult to get an even mix the other way. Having said that, I use the Resoltech glue, which has the filler already added to the resin. But, it is not too difficult to get the mix moving with a decent cup, like the Greek Yog ones. I did tests for the various joints, with precoating unfilled resin before the filled version. Busting the joints always showed the wood failing, so I have no prob with using the prefilled version.
DW
DW
Sticky Stuff
Well-Known Member
Epoxy Resin does not have a Catalyst (ie something that simply starts a reaction) Adding more will give you more start points so the time it takes for the full reaction to happen is significantly shortened and visa versa.
Epoxy resin has Hardener, a component that must be added at the correct volume for the full hardening process to take place.
If It says 4:1 mix ratio that is because 1 volume of hardener will react with 4 volumes of Resin if you mix in more hardener you will simply have a volume of unreacted (soft) material in resulting product or visa versa.
Because Epoxy need these resin/hardener links it is always best to get the resin and hardener mixed together well to enable good linking prior to adding any fillers.
The other issue of adding fillers first, is that all to often there is some bright spark that adds copious amounts of the filler powders thus increasing the volume of the resin and then mixes in hardener to the original volume ratio.
Epoxy resin has Hardener, a component that must be added at the correct volume for the full hardening process to take place.
If It says 4:1 mix ratio that is because 1 volume of hardener will react with 4 volumes of Resin if you mix in more hardener you will simply have a volume of unreacted (soft) material in resulting product or visa versa.
Because Epoxy need these resin/hardener links it is always best to get the resin and hardener mixed together well to enable good linking prior to adding any fillers.
The other issue of adding fillers first, is that all to often there is some bright spark that adds copious amounts of the filler powders thus increasing the volume of the resin and then mixes in hardener to the original volume ratio.
DownWest
Well-Known Member
I think that any of us who actually use the various resins understand that. I don't think anybody was confusing the the mixing of époxy resins with polyester catalyst.
usernamenotvalid
N/A
Why I do: Because as soon as you add the hardener the clock is running. You can pre prepare a few "batches" without all the measuring and pratting about with gloves
and other PPE and sticky stuff going on while pouring, filling shaping or whatever. Particularly for the sake of the inexperienced every moment you have you will need. I did specifically mention mixing it more than you might think it would require. I often mix with graphite powder. An absolute bitch to combine thoroughly. Some woodflour can take a good few minutes to completely mix. The way I do it the additive is already halfway to being mixed before the reaction commences.
There is nothing to prevent you marking the measuring cup out with a marker pen for more than one amount. How is that difficult? There is no amount of anything left on the side of the measuring cup because nothing apart from a clean empty cup went into the measuring cup. The resin and hardener/ additives all went into the fresh clean cup INSIDE the measuring cup which you re use with another fresh one inside it next batch. Op appears inexperienced I was trying to give him an option that does not require a great deal of thought/expense... So long as you READ the instruction. If he owns a pair of digital scales his wife is happy for him to use and get covered in resin fine.
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vyv_cox
Well-Known Member
If he owns a pair of digital scales his wife is happy for him to use and get covered in resin fine.
In UK we have some stuff called polythene. In sheet form we can cover things like scales with it to prevent inadvertently dropped stuff like resin from getting over them.
FairweatherDave
Well-Known Member
bigwow
Well-Known Member
+1 I put my scales in a polythene bag
Greenheart
Well-Known Member
I use a small digital scale instead - idea actually put into my head by Dan Crane of all people
:biggrin-new: I'd like to make it clear that Pete gave me a good deal of advice regarding epoxy, which I value very much...but speaking for myself, I've never owned or used a small digital scale, for any purpose!
I bought the West Systems plastic pumps without thinking, when I bought the 104 'junior' epoxy kit. They worked satisfactorily, but I can't see those same, cheap syringes on the Force 4 site tonight...much costlier alternatives seem to be offered now instead. Are these the subject of this thread?
I'll have a fair bit of epoxying to do before launching this season. I must say that I doubt I was particularly accurate with the ratios in previous work - is it really so important?
prv
Well-Known Member
I see now. I didn't follow your link, just what was in your post.
I'll still be using my scales though
Pete
prv
Well-Known Member
And in China they have something called eBay, which they use to sell us round-eyes perfectly good digital scales for under a fiver delivered
. So I have a set at home which get used for weighing small parcels and the lifejacket cylinders each winter, and another set in my fibreglassing box.In the kitchen I use my granny's old cast-iron balance and weights
Pete
VicS
Well-Known Member
.
In the kitchen I use my granny's old cast-iron balance and weights
Pete
gosh Id not want to be messing about with all those ounces and pounds.
prv
Well-Known Member
I don't mind. Granted I'd be equally happy with metric weights - never occurred to me to get some until now, do they exist? Not sure what steps would be best, the stack of pounds and ounces add up neatly to all common weights.
What I like is the way you use it - put the desired weight on the platform, then tip flour (or whatever) into the bowl until it drops. Dead simple, and feels far more natural for cooking than watching little numbers flip over.
EDIT: Seems you do get metric scale weights, the usual set being 500g, 2x 200g, 100g, 50g, 2x 20g, 10g, 5g apparently.
Pete
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VicS
Well-Known Member
Certainly can
Here's a set that goes from 100g down to 1mg ( although I did not manage to get the small ones in the picture)
The trouble with some of the battery powered electronic balances is that they switch off an bit too soon.
That can be a real pain at times esp if you'ved tared the container. My kitchen scales are like that.
usernamenotvalid
N/A
Nope. +/- 10% with a 2/1 mix. Unless you're building a space shuttle.
Digi scales at a fiver and you still need something to mix the stuff in. Time for scales to arrive from ebay say a week. Batteries may or may not be included. Or walk over to poundland and buy enough plastic cups. Oh, you have to get them anyway. Carry on keeping it complicated.