The road to filled wood

[DaveInOz]

I have heard about filling cracks etc in wood with bitumen putty then sanding to get a gum vein look. I think this would look fantastic in the gidgee.

So far the only bitumen putty I can find has been the non setting type for roofing etc. Can anyone help me as to what to do and where to get the product.

[silentC]

Don't know about that but I've tried two methods that both work:

1. Get some casting resin
2. Get some casting resin and some black oxide powder (used to colour grout)

The first gives you a clear filler so the natural colour comes through and you can see into the crack/vein/void. This looks awesome. You get a real 3D look.

The second gives you a black filler that hides the 'internals' of the crack.

Once the resin has gone off you can scrape and/or sand it flush.

[echnidna]

I'd use Silent's method as bitumen softens with heat (even the heat from sunlight) which could mar the piece. Even opoxy glue can be tinted rather than mess around with larger quanties of casting resin.

[Eastie]

Before you go down the line of epoxy consider the rosin based filler in "the handbook" (its called colophony or something similar).

Its far easier to work with - scrapes off, sands easily, finishes perfectly and you can do small bits at a time once you've mixed the batch. Similar to epoxy you can tint it any color - for black use something like "lamp black" carbon dust. The only probelm you might have is finding the ingredients (and at an afordable price) - let me know as I have a fair bit lying around if you'd like to give it a try.

The fumes do present a bit of a health risk, but not un-manageable (epoxy fumes aren't that great either).

Cheers.

[DaveInOz]

I didn't check the book :o . Hope I don't get excommunicated :eek:

[silentC]

The casting resin I use is actually a polyester resin. It does scrape and sand easily and once you apply a finish, it looks like glass. The only problem I have with the stuff is that it doesn't always go off properly and you get this sticky mess. Not enough catalyst I suspect. It's meant to be 2% but I get lazy sometimes: "hmm, 5 drops will do" :o

I sometimes use clear Araldyte, which is an epoxy. It works better than the polyester but is more expensive and a pain when you need large amounts.

[JB]

Before you go down the line of epoxy

does rosin have any advantages or differences to epoxy, Eastie?

[Bob Willson]

As I understand it, bitumenous (tar) type products NEVER set. They are actually a liquid that just happens to be very very thick.

[PAH1]

Bob is correct, the drip time is measured in decades but it does have a drip time. The advantage is that it is flexible and therefore will not pull out from the crack with changing humidity. I would not recomend it for anything that would contact food. Working with reactive epoxides (epoxy) is not without its hazards and the solvents used in it are only slightly better, the dust from sanding it is also a pretty fair hazard. If the rosin method does not use nasty solvents I would go that route, from memory rosin does not set rock hard and would also allow some flexibility.

[Iain]

I'm going down the same track at the moment and I need some colophony resin, does anyone have any idea where I can get it?
Neils book does not mention a supplier and a google didn't reveal anything.

[PAH1]

For this exact discussion tryprevious thread (http://www.woodworkforums.ubeaut.com.au/archive/index.php/t-6580.html)

Sigma-Aldrich carry it at $40 per 500g, but you would need to set up an account etc with them. Calophony and rosin are interchangeable but a local chemist knows and pronounces it as "resin"

Another potential source of supply is the music industry, I have just been given a lump of material to use-no charge because it was not of musical quality.

[Iain]

I did a search on that thread but it shed no light on suppliers, thanks for your input.

[PAH1]

I did a search on that thread but it shed no light on suppliers, thanks for your input.

Sorry I just meant as a start to where to look. I was not looking for rosin untill your post and within 30 min had located the source, driven there and got it. Sigma-Aldrich is a reliable if sometimes slow supplier, the chemist I rang said he normally had it in stock but does not currently have it but that ringing around other chemists would have some somewhere, the art people were not that much use, although I was given a company to contact in melbourne (Langridge-no more contact details than that!). It was previously the stuff that gymnasts and weightlifters use on their hands for grip, I did not get that far in my enquiries as I had by that stage found the stuff at the music store.

[Iain]

Sorry, upon re reading my response seems a little curt, it was not intended that way, I meant to say thanks for the input re the supplier as I had done a fair amount of googling this morning to no avail.

[markharrison]

Rosin is used by bowed string instrument (violin, viola, cello etc) on the horsehair of a bow.

I have no idea how expensive it is but if you only want a little bit it might be worth the expense. Alternatively if you know a bowed string instrument player, ask if they have a broken bit. Rosin is fairly brittle and I have often seen players struggling with little bits that have broken off.

[Richardwoodhead]

This input is late in the discussion, but I've had great success in creating "gum veins" by just making a mix of 2 pack epoxy resin glue (West System or Con Glue, but probably any 2 pack epoxy would do), then adding black brickies oxide. And working the mix into the crack or hole. It's hard, sands perfectly and finishes well. If it's a BIG gum vein / "hole", I've used clear resin fill - the wood hole effect is somehow effective.

I use the same technique for all kinds of defects (splits etc) in various colour woods by using different coloured oxides, or mixes of oxides. There are quite a few colours available - and by experimenting with mixtures you can create just about any particular wood colour.

[stevephillips]

Ive had some success using 'epo clear' (two pack resin) and crushed charcoal to fill some of the HUGE cracks and valleys in the Marri outdoors table Im making.
Ive had some problems with a suitable finish if anyone can help. The marri just soaks up gallons of oil finish and refuses to polish. :mad:

[Richardwoodhead]

Steve, I've been down the same road trying to oil finish Marri (Organoils, Danish Oils, etc). Forget it. They all end up dull and flat and you lose the feature of the timber. Even if you work at it for weeks. Then I tried a Tung Oil / urethane mixture (just bought some tung oil and monocell 50/50 and mixed it. Two coats with a 320 grit sand in-between worked well.) Then I discovered Feast Watson Floorseal (a tung oil and urethane mixture) which if you spray on to the Marri (again 2 coats, with a 320 grit sand in-beteeen coats) comes up really nicely. Satin finish but very hard, durable etc. Then I discovered spray on lacquers (30% or 40% gloss Becker Acroma from 22 Services in Perth) - and that did the Marri more justice than anything else. But you need a spray gun set-up.