Coffee fill

[masoth]

I hope I've placed this in the right area.

When filling a void should coffee be "washed out" first? I imagine the answer is 'yes' but I don't want to make some silly error, and what glue is best CA, epoxy, or soomething else?

soth

[Skew ChiDAMN!!]

I gather you're using used coffee grounds? I can't help you there then, haven't tried that for myself. I have used whole and/or crushed coffee beans though.

As for the glue, I prefer a casting epoxy. With coffee grounds CA would probably be suitable, but crushed beans are pretty chunky and leave large gaps that CA doesn't fill well.

Casting epoxy is better than something like araldite as it it's thinner, flows nicely & has good working time, whereas araldite is thick and viscous, trapping air bubbles and too short a working time (even if it takes 24 hours to fully cure) which makes it frustrating to use.

PS: You'll probably get more responses if you move the question to the woodturning forums. I dare say it's way more popular among turners than with any other form of woodwork.

[joe greiner]

It depends on the appearance you seek. I prefer fresh grounds without washing. And clear epoxy, although yellowing might not be a major distraction. The mixed epoxy dissolves the colouring in the grounds, same as making liquid coffee, for a dark brown matrix. I fill the gaps proud of the final surface. The final cuts and sanding slice through the hard part of the "aggregate," to expose some lighter material. Final result is a small-scale version of terrazzo. Use a jeweller's eye loupe for best appreciation.

It probably works on flatwork too, so I'll vote against moving, except for posting a link to this thread.

Cheers,
Joe

[masoth]

Thanks to both of you.
I'm building a bookcase for my grand daughter and one side has a void that needs filling. Coffee grounds will match the present colour of the void, I think.
What I thought to do was enjoy a few good brews, save, and let the grounds dry before using - this before finishing the surface. The bookcase will be finished with shellac, or something similar.

soth

[CameronPotter]

I have done this a few times with great success (better than I expected).

I used a multi-step process to fill a burl with a LOT of holes. The fill was flawless in the end. I don't usually say things like that, but it was. However, I have also had some trouble with this in the past as well, so it isn't foolproof.

I used coffee grinds that were VERY dry. This takes a long time. However, you could probably speed the process by baking them in your oven (and I dare say it would make the house smell nice too). However, be careful as with high surface area to volume ratio they will want to burn.

The process was:

1. Flood the crack/void with thin CA to stabilise it as much as possible.

2. Use thick CA mixed with the coffee grounds and PACK it into the crack/void as much as you can. I heartily recommend disposable gloves for this as you may find yourself wanting to tamp it in with your fingers. Make sure that it is tightly packed in and that it protrudes well above the surface that you want to finish on. You have to cut through the mix to make it work best. There should be little or no gaps.

3. Flood again with thin CA (or optionally medium CA depending on the gaps that might be visiable).

4. Cut back carefully - you don't want to crack the glue and chip out the coffee.

5. If there are any gaps, go back to stage 1 and continue.

NOTE: Do not use CA accelerator as this hazes the CA and can cause bubbles.


Two words of warning:
1. This uses a lot of CA (and you probably want to use decent quality stuff). It might not be a good option for a big hole in which case an epoxy would definitely be better and cheaper.

2. This surface will have a very bright finish if sanded to a high grit. This may be hard to match without a lot of work. But at least it gives you something to aim for... I did this on the lathe with Shellawax glow and it worked well.

Cheers

Cam

[Skew ChiDAMN!!]

Just recently (in another thread) I did some experimenting with a bowl and large voids. Being heavily figured, I wanted the fill to look natural...

...and the winning combination was 5-min araldite & instant coffee!

I posted earlier that araldite tends to dry cloudy & full of air-bubbles but that was what I wanted. With the instant coffee imperfectly blended through (enough to get the colour I wanted, but not enough to dissolve everything) it has come up with a very natural looking resin, but without the risk of bits falling out.

It does have air-bubbles and surface imperfections, especially after wiping down several times with a wet rag to dissolve any exposed instant coffee lumps, but CA has filled those nicely.

I wouldn't want to do this on a large area or a void wider than, say, 1/2" but for resin veins it works very well. I'll certainly be using this method again... looks good and is cheap!

[CameronPotter]

Yep. Looked very nice indeed. However, it also depends on what you are aiming for... I don't usually want to have the bubbled resin look - but there are times and places where I would and I will store this away for just such occasions.

[masoth]

Thanks all - very much the info I need. I now feel more confident to proceed.

soth

[Sawdust Maker]

As a word of warning
5 minute epoxy plus coffee grounds into a largish void won't work - when I tried it frothed up and, well, didn't work. Went a sort of greyish colour (and frothy) as well

[Skew ChiDAMN!!]

A (rare) case of Instant is better?

[hughie]

Well for me I use the grounds to make coffee then dry them out and use the grounds on bowl voids etc. As for glue to date I use CA or super glue just to take advantage of the drying time. It works ok although the CA does not like to wick in on the grounds right away.Will look at getting a thinner variety.