Resin for cracks

[Maca]

I've made a couple of small bowls from some cherry which was cut in the spring of this year.  Even though there were no cracks in the blank, when I started turning the outside I could see cracks but decided to continue to finish them.  I left the walls a bit thicker than initially planned just because I was worried they would come apart on the lathe.

Anyway, as the wood was only partially dry the cracks have opened up a bit more, they are about 1-2mm at worst.  They haven't lengthened though so the photo attached shows the length but they are a bit wider than they look here. 

I don't mind the cracks but these are being given to a relative who asked if they could be filled so because I've never used resin before I want to ask the group for advice on good brands of resin and best way to apply it.  I don't have a pressure pot which I've seen a lot of people use and don't intend getting one.

Thanks in advance.

[bodrighywood]

I never use resin, I use various metal and glass powders and very thin industrial super glue. Fill the crack with the powder, in layers, each time dropping some of the glue in. Build up until slightly proud and you have what looks like a pure metal or glass strip in the split. Make sure that you seal the wood round with sealer of something fist as the glue can stain the wood.
Not the beast image but this is an example with brass

Pete

[Maca]

That looks good.  Do you have vendor info for the materials you use?

[fuzzyturns]

Pete's advice is probably best for small cracks like these, as the thin super glue will penetrate nicely into the cracks. For bigger cracks and voids you can make a mixture of epoxy resin and metal powder. This should be about 2/3 powder and 1/3 resin (which has to be pre-mixed first!) to give a thick paste, which can then be pressed into the cracks/voids.
There is a fine balance between getting a paste that will fill the voids, i.e. not too thick, and getting a decent metallic surface (which requires a high metal powder content). Pretty much any decent epoxy resin will do the trick, and since you are using a metal powder, the colour of the resin is not important.
There are also epoxy resins available that are clear and can be mixed with colours to achieve a different effect. Google is your friend, but be prepared to spend around £50 for a decent kit.

[bodrighywood]

I get my metal powders from here and the frit or glass powders from here. Being a bit of a skinflint, kf the split is quite wide or deep I fill it part way with sanding dust (I keep bottles of that handy as well LOL) and top up with the megtal or glass. Personally I have never been able to get a good metallic or glass like finish using resin or epoxy though as Fuzzy says some manage OK.

Pete

[Twisted Trees]

As above really until the splits get to 6mm or bigger resin is a pain in the backside.

Most epoxy will get quite hot when curing, and will often shrink which is why the resins used in wood projects especially when used in thick layers are very expensive cold setting resin with minimal shrinkage.

Cherry moves and splits often, especially when cut into the end grain, I like to cut it thin and let it distort sometimes this can be disastrous or disappointing, but just sometimes it is wonderful... well I like it!

BUT I suspect from your pictures that those splits are not real or finished! they will be blocked by fibres which will stop the metal or glass dust from getting in neatly so you may have to scrape them a bit. Also if they haven't finished moving you may find there is a gap next to your filler in a week or two.

Cherry is a rewarding timber, smells great when you are cutting it distorts when put in a modern warm dry house and like oak it will often split part way through but maintain it's integrity.

[Derek]

For fine splits, I use basically the same as Pete except I use the thin CA and apply that first then put powder on top then tip it out and repeat as i have had it where I tried the powder first and then the glue just sat on top and sealed the powder in when turning or sanding back the loose pwder came out.

[bodrighywood]

For fine splits, I use basically the same as Pete except I use the thin CA and apply that first then put powder on top then tip it out and repeat as i have had it where I tried the powder first and then the glue just sat on top and sealed the powder in when turning or sanding back the loose pwder came out.

Agreed, if you completely fill the crack then add the glue it just hardens the top and can fall out hence the need to build up in layers. Not sure it matters whether you put glue or powder in first as long as it is layered. Same reason for using the really thin stuff as medium or thicker doesn't penetrate the poder. Avoid the shop stuff, very expensive and IME nowhere near as good as the industrial stuff.

Pete

[John Plater]

Agreed, fine cracks can be dealt best with CA glue, do your own experiments but only after sealing the timber on either side of the crack so that the CA does not stain it. For bigger cracks and voids I came across a car body filler based on epoxy resin with fine glass fibre strands. Epoxy sticks to wood better than polyester resin and the glass fibre strands offer strength and gap filling advantages. I found black or with no colour which could be pigmented to suit.
ATB John

[BrianH]

don't forget the wood may well continue to move around whatever solid filler you use and the piece may then crack up worse than when you started.
Brian

[Maca]

Did a test bowl to see how it worked out with the aluminium powder.  The thin CA glue was quite difficult to use without one of those fine nozzles they sell so it went a bit messy but remounted it and sanded it back.  Think it worked out well enough to try some more (photo isn't great but you get the idea).  Thanks for the advice, got another aspect the bowls now.

[bodrighywood]

The glue I buy here comes in bottles with sealed nozzles that you cut open to suit. It is industrial strength and comes in thin, medium and thick versions. I use thin for filling splits etc, thick for general adhesive work. Best I have yet to find. Also I have a few pieces that I glued up years ago that are still sound. Many CA glues become brittle after a while and fail if pressure is applied.

pete

[hughie]

OK from my perspective, you  need to decide if you to hide or make it a feature. Me I always make them a feature because I'm lousy at trying to hide them.
 Resin has it merits as  do most ideas but much depends on the size of the crack and the type of timber your using.  Very small ie 1mm and down on hardwood I often use CA as the clear CA and the dark timber  will blend and largely disappear.
Fillers, well its up to your imagination. I have used ebony dust, metal powders, ground up shells from nuts,  pistachios shells work for me, coffee grounds used and unused, bark ground finely and on some big cracks loose small pieces of bark and so on.
Resin can be a challenge if timber in question moves a lot as the resin will eventually pull away. There used to be a  soft resin used as damp proofing in bathrooms it was ok. But technology has moved on and I dont see it for sale any more. I think Howards https://www.howardproducts.com.au/products.html  and  https://www.howardproducts.com/ used to have a soft resin designed for wood havent heard much about it lately