Epoxy resin

[JasonPD]

Hey guys, need some advice. New to using resin, so I have a question. I have a piece of Redgum I want to fill a large crack, however I've noticed this goes all the way through in areas. How do I fill this space without the resin from spilling out the other side? I'm thinking duct tape behind so it's waterproof so to speak, but will this affect the finish of the resin when I pull the tape off? Will it be nice & glassy also? Or is there another method? Thanks

[Master Splinter]

Duct tape works fine, but you'll get whatever finish the duct tape has... so on the sticky side it will be a little rough. Just sand it as you would sand normal timber once it's set and overcoat with your final finish.

[dai sensei]

Duct tape can come undone from the heat of setting and if there is any dust/dirt/oil on the surface. If there is a lot of resin, the shear weight of the resin can also pop off duct tape as it doesn't stick extremely well with bare timber, very messy. I find it is best to hot melt glue on small bits of ply

[shanesmith80]

I just use masking tape to cover up cracks before I pour with epoxy. Haven't had any major leaks and cleans off easy as long as I don't leave it to long.

Post below shows an example

http://www.woodworkforums.com/showthread.php?t=166179

[BobL]

I just use masking tape to cover up cracks before I pour with epoxy. Haven't had any major leaks and cleans off easy as long as I don't leave it to long.

For large gaps I've also used just masking tape (2/3layers extending the tape ~100 mm either side of the hole but usually don't fill it all in one go. Just pour enough in to check for leaks and seal the bottom of the hole. Once that is established then completely fill the hole. The larger the hole the more the tape sags but the excess is usually just sanded off. If its really sagging I support the tape from underneath by clamping a piece of ply. I must try DS small bits of hot glue ply idea next time - that sounds like it would be the go.

[soundman]

what you use can depend on what resin you are using ...... some resins have no problem with typical tape adhesives .... others behave like solvents on the adhesive and the tape simply comes off or leaks.

The single most important thing to understand is .... fill your cracks before any surface preparation ..... thus any bleed or surpluss will be machined or sanded off.

I have tried a variety of things with various effectivness .... gluing stiff paper, card or as mantioned bits of ply or timber to the other side is the safest ..... then machine it off

sometimes you will need to have several goes and from both sides to get filled flush.

remember if the epoxy is unthickended it may run some way into the crack and may be absorbed by the timber ..... this is not a bad thing ...... let it go off before filling again.

How will the filled epoxy look when finished ..... that will depend on the epoxy and if you have filled it and with what.

Some epoxies are crystal clear, some are slightly tinted some are slightly milky.

cheers

[Christos]

I have used masking tape on the underside to fill cracks and holes.

Make sure that you take your time in taping this up as the last thing you would want is to have an unexpected fountain.

If this is a large crack as you have mention then might be best to fill in stages and normally in well ventilated area or outside.

Depending on the feature you are after you can also tint the epoxy to what ever colour suits the piece.

[JasonPD]

Thanks a lot everybody. That's some great advice. I'm currently using feast and Watson from bunnings. It's a clear finish and I love it. It's pretty expensive though. Is there a cheaper product out there that's as good? And where do you buy it from?

[RoyG]

The biggest issue that I encounter with clear epoxy filling, that hasn't been mentioned in this thread so far, is that as the epoxy is absorbed by the wood, a certain amount of air is displaced from the wood, and this air bubbles up through the epoxy as it sets. I have tried popping the bubbles by waving a LPG Gas Torch flame a few inches above the surface, which pops the bubbles nicely. However, that can be a very tiresome process as the resin can take up to an hour (longer in cooler weather) to set enough to stop bubbles from forming. If you don't manage to pop all of those bubbles, you'll end up with unsightly bubbles visible in the resin, or you'll end up with resin bubbles set on the surface.

What I now do to overcome the bubbles problem, is to coat the inside of the void, or the through hole, with a brushed on layer of epoxy as the first coat to seal the surface. With a crack, brushing is usually impossible, but it is often possible to put some resin in the crack, rotate the workpiece a few times to coat all surfaces inside the crack, and then pour out the rest of the resin. With a through hole, I still seal one side off with adhesive tape.

Once the first coat of resin is cured, I remove any adhesive tape used for the sealing coat, and apply new adhesive tape. Then I completely fill the void or crack with resin. That way I don't usually get any air bubbles in the second resin pour. If I do get air bubbles in the second resin pour, it's usually because I've stirred the epoxy mixture too vigorously and have stirred air bubbles into the epoxy. The solution is to stir slowly concentrating on stirring slowly enough to avoid infusing air bubbles in the resin. Another source of air bubbles in the resin can be rapid pouring - pouring slowly helps eliminate air bubbles as well.

Hope that info helps some.

Regards,

RoyG

[Master Splinter]

Cost wise, look on ebay....

http://stores.ebay.com.au/DIY-Composites?_trksid=p2047675.l2563

$155 for 4 litres of tabletop epoxy.

[justonething]

This one is not bad either https://secure.solidsolutions.com.au/view_products.php?cat=6

[JasonPD]

Thanks very much people very helpful cheers