What's the best liquid epoxy available at a reasonable price?

[TheJay]

What would your friend recommend?

 

[Deleted member 174758]

I'll give him a shout and ask. Not really something we've ever discussed in detail TBH. Let you know when I know

Edit: @TheJay my oppo came back to me this morning. He told me that West do have a syringe pack #807 but that your local chemist should also be able to sell you a syringe (less needle) for maybe 50p or a quid. He also suggested that maybe you should go and look at a supplier's site such as Paint Marine in Romsey where he has an account as they carry the full range of West stuff

 

[TheJay]

Thank you. Do you know which size syringes I should be using?

 

[Deleted member 174758]

That depends on how much you are making up at a time, so TBH in your case I really don't know. They aren't that expensive so if in doubt why not just buy the West 3-syringe set or just get a couple of syringes (say 5ml and 20ml) from the chemists? 5ml is basicslly s teaspoon's worth while 20ml is something like a dessert spoonful, I think

Where I've used West System it has been for tasks like laying up glue bonded structural components, etc for which it was necessary to buy-in gallon containers with the pump measures because I'd be laying on a litre or more of epoxy in one session. For filling I've just used auto sprayer's measuring cups to measure out a plastic paint kettle to mix, because I had some, and spatulas or stopping knives to apply because that's the technique I was taught in the dim and distant past

 

[TheJay]

Thank you once again.

Is the idea with the syringes to premix the different parts into the syringes to get them into the tight spots? I presume it wouldn't work very well applying each part individually from different syringes because it wouldn't mix properly?

I could only see a 2 syringe set when I looked (10ml and 50ml).

 

[Deleted member 174758]

The syringes are used to apply the resin, you still need to mix conventionally (i.e spatula and mixing tub) then pick it up in the syringe. If you don't mix the resin and the hardener thoroughly it will not cure properly. The same is true of any 2-pack material.

Exact measurement of the two components isn't absolutely critical, but it does need to be somewhere near right - you normally just use "rack of eye" (i.e. visual comparison) - if you are slightly light on hardener curing time will be extended a bit, if you are slightly heavy on hardener the curing time will shorten a little bit. The reason why you use the measure pumps on larger jobs is just to speed up dispensing - they don't measure precise amounts, but they are close enough to ensure a consistent mix

 

[TheJay]

Thank you for confirming. I've ordered using the links I included before so I have everything I need.

I'm used to mixing two part filler, so this shouldn't be too difficult. I learned the hard way that not mixing the hardener in properly can result in parts of the wood filler not curing at all, so hopefully this should be easier with that in mind.

 

[TheJay]

Partly from memory you need something like the basic #105 resin / #205 hardener pack (they did some smaller "starter" packs which used to be £25 or so a few years back) but in your case I think you may well need the colloidal silica filler #406 as well, at between between about 40:1 and 10:1 mixed resin:filler ratio (the filler was about £8?). Using a filler gives improved load capacity and screw pull-out resistance as well as making a structural strength repair with good smoothness. You also use that filler when laminating making fillets and fairing-in (i.e where smooth sanded contoured surfaces are required). West also make low density and micro fibre fillers. In addition to the resin, hardener and filler you'll need measuring cups and disposable mixing sticks (these don't need to be West, where you are just oaying for their name on the cup - your local car paint supplier should be able to supply these really cheaply). One plus point of West is that once cured it can be routed, but you do seem to get a better surface with the filler

Please bear in mind that the last time I bought West stuff was pre-Covid, so prices could well be up 20 to 30% on the figures I quoted

As an aside, may I comment about routing technique? If you want a smoother bottom to your cuts tape a 1mm packer onto the top of your turret and make a first cut by plunging down slowly and then hogging away most of the material. Withdraw the router, unplunge, remove the 1mm packer and replunge to full depth, keeping the router moving as you replunge. Don't use excessive force making your plunge cuts. Hogging the waste then making a finishing cut means you can avoid those annoying cutter circles more easily

I'm struggling to figure out how to practically get the correct quantities of each. Let's say I want to fill a 10ml syringe. Can you please tell me what the quantities of each would be?

 

[Deleted member 174758]

According to my notes:

105 resin with either 205 fast hardener or 206 slow hardener, ratio is 5:1 (resin:hardener) by volume or weight - so 25ml of resin to 5ml of hardener

105 resin with either 207 clear hardener or 209 extra slow hardener, ratio is 3:1 (resin:hardener) by volume (3.5:1 by weight) - so 15ml of resin to 5ml of hardener (by volume)

 

[TheJay]

That's the mix ratio of the two components, then divide the total combined volume or weight by 40 to know how much colloidal silica to use?

 

[Deleted member 174758]

AFAIK there isn't a set ratio for the filler - you just mix the epoxy components in the above ratios, then add filler to the required stiffness for the job at hand by shaking it into a mixing tub, mixing it in then seeing how stiff it is and adding more as required (in other words only add a small amount at a time). For filling you need a similar consistency to fairly fresh 2-pack car body or wood filler, i.e. a stiff mix rather like a stiff cake mix (in other words it doesn't slump but is stiff enough to spread with a stopping knife). I realise that as a description that might not be all that helpful, but the following video show the sort of consistency I aim for @ 0:58:

There is a bulk mixing table here, but TBH I never use it. Most of the time when I've been using West System it has been applied in unfilled mixed state (for laying-up carbon fibre reinforcement in gluelams, etc). Only occasionally have I ever needed to mix up a filler, and then I just tend to eyeball the quantities.

A bigger question is how do you know what actual quantity of filler you need? Sorry, but when I'm filling voids in timber with 2-pack I tend to eyeball the amount and just mix it, like a lot of people. Make too little and I know I have to mix some more (not a problem, I think). Make too much and I end up chucking stuff out. Main thing for me is only to measure what I can lay in about 15 minutes as the open time is 20 to 25 minutes with the standard hardener and you lose maybe 5 minutes mixing it. So sorry, no filler ratio - hence my earlier confusion.

Anyway, it looks like I'll be using West System again myself in the near future (as a filler and for repair bonding) as I have a very rotted timber bell cupola to repair, in-situ, where the conservation officer is insisting that we don't remove and replace original material, just strengthen it. Site survey Monday...