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MBUMIK
22nd January 2010, 02:38 PM
i have been playing with embedding things in resin

the first picture which is the last thing i tried is a black resin base with a bead embedded in clear resin on the top
- i poured the black resin into the mould (a piece of conduit with gaffa tape on the bottom) waited for around 20 minutes for the resin to gel or more
- i poured a small amount of clear resin into the mould then placed the object into the resin and poured the rest of the resin over the top
- all was going well and when i checked about 2 hours later the resin had a crack in it which you can just see at the top of the pickie

the second picture and third pickies are both the same with the same result
- i found a piece of red gum and turned it to round on the bottle stopper mandrel
- i then cut up a paper cup and wrapped it around the red gum and gaffa taped it in place to seal and form a mould on the top
- i poured a small amount of resin into the mould and then placed the object into position and covered it with the rest of the resin
- all was looking good until the next day when i found that air bubble had leaked in between the redgum and the resin,

all were to be bottle stoppers

i did try sealing the top of the wood with CA which gave less bubbles but still bubbles

i am going to try next with pressure although one will have to place them carefully into the pot to stop the object from going off centre

another point of intrest is that the 2 objects in the first and second picture are both the same, both started off silver in colour:o

i am very interested in everyones thoughts and ideas

thanks for reading

MIK

rsser
22nd January 2010, 02:43 PM
in the 1st you prob got a crack because the resin heats up as it goes off and you had two layers heating and cooling at diff rates

MBUMIK
22nd January 2010, 02:59 PM
thanks Ern

i was thinking much the same as well, the reason i did it this way is i thought if the resin had set completely then it would stick together

i am planning to try again the same as above but with pressure and also letting it set completely before adding the top layer

anything is worth a try

MIK

NewLondon88
23rd January 2010, 11:55 PM
My eyes aren't what they used to be, but looking at the 2nd and 3rd photos it looks
like either bubbles from moisture (how humid is it where you are?) or the CA you
mentioned might be off-gassing into the resin.

If you want to get some idea of the off-gassing, try taking an old pen kit (one of the ones
where you made a mistake and set it aside .. missing a spring, broken transmission etc)
and glue the brass tube into a blank. Put the blank aside for a few hours like you would
if you were making a pen.
Then put the blank back into the bag and seal it up.Come back tomorrow and check on it.
You should find your pen parts are an opaque white over the surface. That's the CA
off-gassing, and it continues for days. (some have said a week, but I don't really know)

It wouldn't surprise me if that gas reacts with the resin in some way, but if nothing else it
is a source of new air bubbles..

dai sensei
24th January 2010, 10:25 AM
Yep, too much heat will cause it to crack, but you can just use a bit more resin to fill it. As long as you do not touch the surfaces of the crack, and nothing gets on it, you will not see it. Try using less catalyst, in summer less is required, and this reduces the heat reaction (but setting may take a bot longer). You can also reduce the amounts of each pour.

You do not need to have a sticky surface between pours (from not going completely off) to have resin join without seeing the joint. You can do it after it has gone off, but the joint does have to be completely clean, so no dust or particles.

Timber is porous and will extrude air bubbles if there is no pressure or unsealed. Under pressure the resin is forced down, alternatively, use a bit of resin to coat the timber and seal it like a tack coat prior to the main pour. CA is OK over the top of or after the resin, not the other way around due to the fumes as discussed above.

Cheers