Filling defects with casting resin

[Bodgy]

Just finished another blue gum table. I got the 8x2s from Wongo which form the top and they had extensive insect, rot etc damage (which I like).

I usually fill these holes with an opaque filler, either casting resin or epoxy tinted (usually black).

This time I thought I'd try clear, the depth of the holes, cracks etc should look interesting.

Unfortunately, as usual, disaster.

Heres how I did it and my mistake:

I sealed the damaged areas with hard shellac, as the casting resin will just soak into the wood otherwise. When dry, I carefully poured in the casting resin (un-tinted) gently stirring to encourage the air bubbles to rise and disapate, I over filled ensuring the meniscus of the resin was high enough to ensure no hollows when sanding back, and dammed around the holes where necessary.

A few days later began finishing the table top.

I looks bloody awful! Problem is that whilst the body of the casting resin is clear, the rough nature of the sides and bottom of the holes trapped air, which the stirring did not release. Consequently these trapped bubble at bottom and around sides look dreadfull, they appear as a white, rough stain at in each of the filled holes - awful.

I'm going to stick to opaque fills in future, you simply dont know what the end result will look like until too late. Alternatively, I guess you could dress the insides of the defects - but who wants to do that??

I'll try for some photos but the gloss finish probably won't show the cock ups on camera.

Hope this may help someone else.

[DJ’s Timber]

Bit late now, but one way to get rid of these air bubbles is to heat the cracks and holes with a heat gun before filling, the heat makes all the air rise. Have done this with great results. Also I use Epoxy Cast 303 which is ultra clear.

[Bodgy]

Doh!

Sounds like a solution.

Does Epoxy Cast 303 have a more workable mixing ratio than the stuff from Bunnies?

I'd like it to go off a bit quicker but the hardener is around 1% of resin which makes it very difficult if you're only mixing 50 ml or so, to slightly adjust the quantity.

Sorry, ignore last. Just browsed the site and its 2:1 ratio, which is much more workable.

[mickspry]

Hey mate the hot air gun will work to lift the air bubbles, another trick I have used is to pass a lite match close to the resin just after you put it onto the hole. this brings the air out quick smart however two things to look out for fumes are not good also the resin will be very brittle not a problem on a flat table top but could be a hassel on a leg or chair back.
Give it a go great results this way
Mick

[Frank&Earnest]

Hi Bodgy, the title got me interested because I am thinking of mucking around with casting resin in the future. Would it be possible, in a case like yours, to dig down the clear resin surface a couple of mm and refill it with opaque tinted resin to cover up the bad result and obtain the usual finish?

Also, what is the name and cost of "the stuff from Bunnies"?

Thanks
Frank

[silentC]

On the side of my tin of Norglass casting resin, they recommend painting the surface of non-porous objects with resin with no catalyst added prior to pouring. This is supposed to help stop air bubbles forming. This leads me to believe that the reason I've not had the problem you describe is that I haven't applied anything first, and so perhaps the air bubbles are being absorbed by the pores of the wood? Not sure about that. Anyway, it might be worth giving that a try. It's worth persevering because the effect can be quite stunning.

[Bodgy]

F&E

1) Probably not practical to dig out and refill with tinted resin. The surface is very, very insect/rot effected. Probably makes more sense to invert the table top and finsih whats now the underside.

Not sure what to do. There's always a tablecloth.

2) Just ask for casting resin in Bunnies. They only have one sort -at least in our local. I'd suggest you check out the Epoxy 303 as per 2nd post here, even tho its a bit exxy. As per memory about $20 for 500 ml for the Bunnies stuff - Norglass I think

Measuring and mixing 0.5 ml of hardener for a 50ml mix is a nightmare.

Silent

The first time I did this I did not seal. Your logic can't be faulted but whilst I had no bubles I could see, the timber just constantly suck up the resin. Took 3 goes to fill the hole, even then the resin sunk to leave hollows. Additionally the resin is such filthy stuff to work with.

Agree it could look stunning. Maybe if you increased the hardener % it could stop the soaking up, as the resin would go off before it all soaked away?

[Frank&Earnest]

Thanks Bodgy. At that price it is not very far from the Epoxy 306. Any reason why the 306 would be less suitable than the 303?

[silentC]

Next time, I'd be inclined to do as you have done and seal it with shellac first but then try painting it with un-catalysed resin first and see if that doesn't stop air bubbles from forming. I seem to remember someone suggesting that on here as well. Also, the hot air gun is supposed to work a treat - haven't tried it but plenty swear by it.

[silentC]

A bit of info on this thread.

[Papillon]

Hi SilentC, I have just started playing with casting resin myself and found the solution to small mixtures is to buy a 5ml syringe from the chemist. They only cost about a dollar and are marked in 0.2 ml increments and the catalyst doesn't damage them at all.
For the resin I use a couple of different sized spoons that I checked the capacity of using water. It's not exact, but the results so far are fine.

Cheers,
Papillon

[ubeaut]

I have used Clear casting resin in the past and had fantastic results. I did however go to a specialist outlet that dealt only with fiberglass and resins to purchase it.

Long time ago but think it was Damar or similar to that. In Mitcham Vic. I have filled holes of all sizes and shapes including one in a coffee table that I carved a platypus and put in the hole before filling it with the resin. I had only one use of it when bubbles were a problem and that was with the platypus when a small bubble developed on one of the wee beasties eyes. It wasn't picked up at the time but looks fantastic (freeky).

The fact that you have whitish stained bubbles seems a bit odd to me maybe you left your stirring a bit late in the piece. I was always able to remove bubbles by simply piercing them with a sewing needle.

I have had great success with the stuff. Turned burl bowls with big windows in them, looks fantastic. I had a table with gold leaf floating in the cracks,tiny stones embedded, threads of cotton and all sorts of other terrific and often very surprising things.

I loved it when I used it some 20 years ago. I'm over it now.

Cheers - Neil

[zenwood]

i only ever use a few cc's (ml) of resin at a time. I draw the resin out of the tin with a plastic syringe, then deposit it in a plastic spoon. Then I use a match and dip it in the hardener and let it get wet, then hold it over the spoon, and let the hardener drip into the spoon. I guesstimate that each drop is about 0.005 ml, so one drop per 0.5 ml is about right.

[MacS]

I don't know if they are sold here, but they would be ideal for your work (I think)

These are round sticks that contain the resin inside, and the catalyst wraped on the outside.They are protected by a piece plastic.

They are about 4" long and about 1" round.

They come in assorted colors, or you can mix your own dry powdered colors in with epoxt and knead them together.

You never will have a problem with pinholes or shinkage as there is no solvent in this filler.

Maybe, do a search, you just might find them here., they are not expensive considering what they can do.

MacS

[MacS]

You may call these fillers by another name, but this is what it looks like.

They are usually sold in smaller size sticks.