black epoxy resin

[shpeedie]

i have just put together an ironbark railway sleeper tabletop and want to coat it in black resin before putting it through a belt sander but am having problems finding info about resin.
Can someone help with these questions:

Any recommendations for a type of epoxy to use on this wood ?
Can you buy black resin or does it have to be mixed ?
Any places in Sydney i can purchase it or get more advice ?

Thanks!

[Bernt]

Hi, use an epoxy resin, fiber glass resin shrinks more (I use west system but brand is not important) any fiber glass shop sells this stuff and you just ad some black pigment which they also sell in little jars. Depending on how deep your gaps/holes are you might want to look into some microfiber to mix in (also in these shops) to stiffen the resin up a bit otherwise you'll be filling for days with lots of sink back. With the microfiber the epoxy resin becomes a very good glue as well. Good luck!

[old pete]

Hi Shpeedie,

Use a good quality two pack epoxy glue such as Techniglue or Epiglue. They are avaialble from marine distributors or fibre glass shops.Quite expensive however! When mixed load the epoxy brew as heavily as you can with black artists dry powder paint colour. The more powder you get in to the mix the easier it is to sand. I make a practice of very carefully masking up the splits cracks etc to be patched so that the minimum of epoxy resin invades the timber that does not need treatment. The cured epoxy is fairly toxic so take care when doing the sanding. You will almost certainly find that you have to go through a two or three application process to refill bubbles or low spots in your first coat of brew. This task takes time and patience. I would leave the resin for several days to fully cure before sanding.

When sanding don't focus on sanding the resin treated areas and leaving dips and bumps in your wake. Put stripes over the whole surface of the panel with a 2 B pencil at 25mm intervals and sand away until all the stripes are gone then apply more stripes and go again. Repeat the dose until the whole surface is flat and flush with the filled areas.

Goodf Luck


Old Pete

[stevemc32]

The bigger places in Sydney are FMS who now look like they're calling themselves Valspar (http://www.fibreglassmaterials.com.au/), and FGI (http://www.fgi.com.au/). They'll usually be happy to answer any questions you might have on which would be the most suitable product.

Other options are the boat places like Bias Boating (http://www.biasboating.com.au/c-101-fibreglass-fillers-adhesives.aspx) and the many smaller fibreglass dealers. I think Carbatec does a line of epoxy also.

[Vernonv]

I have used normal black oxide (what the hardware places sell of mixing with cement) to make black epoxy. Just mix a bit in until you get the colour and consistency the way you want it. Black oxide will never dull or fade.

[shpeedie]

Thanks for the info guys!
I have a few bolt holes in the wood that go right through the timber.
Rather than wasting lots of resin filling them up, can i mix some hard glue and sawdust to fill most of the hole, and then resin maybe 1 or 2mm from the top ?
Or glue a dowel in place and then cover it over with black resin ?

Im hoping the sawdust/glue wont sink overtime causing the resin to crack, thats my main concern.

Thanks

[Bernt]

I would be a bit concerned about having only a crust of resin over the top of soft filling. Buying a small set of epoxy resin and hardener should give more then enough resin to fill a few bolt holes as well and it kind of gives a nice depth to the resin if it is still slightly transparent.

[shpeedie]

OK, but to give a quick idea on how much resin i need. the table is 2.2m long
Bolt holes are 10mm wide and there is about 40 of them going through the wood which is 55mm thick. Heres a pic

http://www.australia.id.au/table.JPG

[Charleville]

It is tricky to estimate what quantity you need on that sort of a metric.

However, as Bernt has recommended, it might be useful to thicken up the first application of epoxy down the holes with some microfibre West System Microfibre Packs : CARBA-TEC (http://www.carbatec.com.au/west-system-microfibre-packs_c11880) to make a paste. I have found this to be very useful in filling the sort of chasms that you are describing as liquid epoxy can quickly trickle away into a zillion cracks in the wood and dissipate quite quickly, albeit at the same time strengthening the wood. At first glance, even the microfibre might not look cheap but a little bit goes a long way.

So I reckon that you could plug the holes first with an epoxy/microfibre mix leaving a bit of room at the top of each hole for the final application of liquid epoxy with the black stuff mixed in.

When you buy your epoxy, remember that two 500ml tins of epoxy resin costs 36% more than one 1 litre tin. West System Resin & Hardener Fixes : CARBA-TEC (http://www.carbatec.com.au/west-system-resin-hardener-fixes_c11830)

So if in doubt about quantities when you look at a tin of the stuff in your hands, you may well be better off biting the bullet and buying the next bigger tin than you reckon necessary because it is a bugger to have to go back and buy another of the same size as before because you needed that little bit extra.

Brand is not so important. Just tell the shop what your purpose is and they will advise.


.

[AlexS]

You could also talk to Adhesive Engineering (http://www.adhesiveengineering.com.au/) in Hornsby - considerably cheaper than Techniglue or West System.

[elanjacobs]

Techniglue and dynamic pigment paste has worked for me in the past. The paste tends to mix more evenly than powder and a little goes a looooong way; 10mL will easily colour half a litre of epoxy.

[GraemeCook]

I routinely use the local fibreglass shops home brew epoxy - about 30% cheaper than and indistinguishable from WEST. They also sell pigment pastes in small tins, that go a very long way.

Sawdust is a great thickener for epoxy - and it sets close to the colour of the sanding timber. Whenever I do some nice clean sanding or sawing I keep the dust - huon pine jar, blackwood jar, celery pine jar, etc. The thickened epoxy is always stronger than the adjacent timber!

A couple of tricks to improve epoxying:

* Epoxy hates water until it cures. Any hint of dampness in the materials will cause epoxy to go cloudy.

* Pre-heat glue surfaces before applying first coat - this aids penetration and minimises bubbles.

* always apply an unthickened penetration coat first. Very occasionally this will not want to penetrate but will visibly sit on the surface. Quickly wipe off what you have done, wash the relevant surface with solvent (MEK or acetone) and re-apply the resin, preferably while the solvent is still wet..

* apply additional coats soon after the first coat has gone off.

Remember, coats applied within 24 hours of each other form a chemical bond, after 48 hours they form a mechanical bond.

Do not sand epoxy until it has fully cured - perhaps two weeks - or the surface will melt and go cloudy.

Follow the safety instructions carefully; Epoxy is nasty stuff and its effects are cumulative as one become sensitised.

Cheers

Graeme

[shpeedie]

Thanks for the info guys, really helpfull! in regards to applying the resin:
I have done some tests and after leaving the resin to cure for about 4 days, sanding back has made the resin go a lighter colour, almost grey, compared to the jet black it was when poured. Is there a way to fix this ? ie finer sanding, or more black pigment.

I also noted that bubbles have formed in the test resin a few mm under the surface.
I pre-heated the wood, applied the resin and used a heat gun to warm the resin and could see bubbles coming out, and then left to dry for a few days. Any tips on getting more bubbles out ?

Last, once the resin and wood is all sanded back, should i apply some sort of sealer to the wood ? Although its hard ironbark, im still worried about water or moisture damage.

Thanks again
Tim

[Rattrap]

I've noticed myself that when i tinted epoxy black then sanded it tended to go more of a grey colour however after a finish is applied it goes back to black.

[GraemeCook]

Good Morning Tim

Been there; done that, etc.....

Possibilities for resin going greyish could be:

* You have not let it cure long enough before sanding, if hand sanding, or

* You have machine sanded creating too much heat which has melted the epoxy, or

* You did not mix the resin/hardinner sufficiently. The slightest hint of stringiness means you need to stir more.

In any case, another coat of tinted but unthickened epoxy should fix the problem.

Bubbles could indicate that the surfaces or the epoxy (or both) are too cold; they must be above 10*C and preferably around 20*C - or epoxy is too thick, or you have been too vigorous with the application brush. Gentle vibrating or tapping the tabletop should dislodge them. Also, it helps to pre-wet surfaces with solvent - acetone or MEK.

As you seem to be experiencing, epoxying is a combination of science, art and a little voodoo.

Cheers

Graeme

[Dengue]

Techniglue and dynamic pigment paste

Can anyone please suggest where I might get this dynamic pigment paste for making black epoxy?

[elanjacobs]

Can anyone please suggest where I might get this dynamic pigment paste for making black epoxy?

This is where work gets it: https://secure.solidsolutions.com.au/view_products.php?cat=14

[Dengue]

Many thanks elanjacobs - this stuff looks good, but expensive, but they want $20 for posting a little 50gm bottle worht $12 via Aust Post to Townsville, NQ.

Do you know if it is water soluble or spirit based, and do you dilute it if you are only mixing up a small amount of epoxy eg 1 tablespoon full?

[elanjacobs]

Many thanks elanjacobs - this stuff looks good. Is it water soluble or spirit based?

No idea. It says to add metho if it dries out. That help?

[AlexS]

You could try black powder pigment from an art shop. I've used it successfully with Techniglue.

[Master Splinter]

Photocopier toner powder works too...

[tony_A]

Off gassing by the wood will cause bubbles in the resin. To prevent this, warm the wood up to about 30 deg in the sun or warm room then move it into a cooler area where the wood will slowly cool down. Apply the resin as the wood slowly cools so the resin is drawn into the wood rather than expanding gas from within the wood being forced out. You want the work about 30 deg so the resin flows well but in a situation where it starts to cool. Dont lay up resin in the sun.
Tony

[Robson Valley]

Another reason the epoxy might have gone gray is simple, microscopic scratches from sanding.
Stone sculptures look like that before the final polishing. Same deal as going from
a 4k water stone to honing a wood carving gouge.

Be absolutely fastidious when you apply the epoxy with good ventilation.
I have not been able to work with that stuff for more than 40 years.
Every 5 years or so I try again.
Usually feel comfortable after 2-3 days.

[GraemeCook]

Be absolutely fastidious when you apply the epoxy with good ventilation.
I have not been able to work with that stuff for more than 40 years.
Every 5 years or so I try again.
Usually feel comfortable after 2-3 days.

If anything, Robson is understating the safety issues regarding epoxy. Some people get sensitised to it over a period of time and it is serious and, probably, irreversible.

A friend who used to build cold molded dinghies as a hobby got highly senstised. If he is exposed to wet epoxy he quickly develops a bright red ring around his mouth, red "racoon" eyes, sweats, elevated pulse, spots and flashes in his peripheral vision and severe migraine that lasts three or four days.

I am lightly sensitised and I get a twitch in my left eye that lasts for about 24 hours and reminds me to be more careful with epoxy.

Rubber gloves or two pairs of latex gloves, minimal exposed skin, eye protection and a good charcoal filter are the minimum that I would consider.

Fair Winds

Graeme

[Robson Valley]

You're so right, Graeme. I would not use epoxy in a cyclone. Nasty #####.
While epoxy adhesives are fantastic, I have no choice but to look at any and all possible alternatives.

The interesting thing is that several of the major automotive makers (Ford & GM)
figured this out. The contact sensitivity to epoxies doesn't affect dark skinned people.
So, everybody in the upholstery & trim divisions was not Caucasian.

[Cliff Rogers]

Only thing that I can add to this is that Feast Watson - Woodstains - Prooftint (http://www.feastwatson.com.au/WoodstainsProoftint.asp) does NOT work for colouring epoxy, the epoxy won't set.... DAMHIK. :D