Epoxy resin has not set off - what to do.

[DownWest]

On old epoxy: I was given a 200lt drum + three 30lt plastic containers of hardener at slightly different mixes and varing speeds. They are all now past their sell by date, so from time to time I do a test piece. Good so far, except for one of the hardeners ( slow) appears to be more runny, smells less and doesn't work at all.
The other mixes do harden at lower temps, like 10°C but takes a while to harden.
For flat surfaces, an electric blanket over plastic sheeting with a plain blanket over the top does work.

Unlike recorcinol glue, which, if allowed to drop below 10° during curing, just lets go. Epoxy will just slow down at low temps, then carry on when it warms up.

 

[MontyMariner]

I'm making 2 x 500mm square panels with 50mm vertical edges, (imagine a tray)

Surely they are small enough to sneek them into the house and leave them somewhere warm for a few weeks. Nothing lost if it doesn't work.

 

[biscuit]

Thread drift alert:
PVA glue can loose considerable effectiveness over time.
On important jobs use a fresh lot, its cheap enough.

 

[jamie N]

Its been unusually cold in Sydney this winter, this morning it was 8 degrees (and my underground workshop enjoys no sunshine) but we are promised a couple of day time temps of 23/24....

You'd a bit of sympathy until you posted those numbers Jonathan......

 

[Neeves]

an update

Based on further advice:

Houses here tend to be built to cope with the extremes of heat, not cold.

I had fondly hoped that once the reaction re-commenced it might continue, even if slowly, overnight - hope springs eternal - but is invalid with epoxy.

They had a good full day in the sun, outdoors, yesterday - they might have improved but that might be more wishful thinking.

I've moved the panels indoors. They are now sitting on the living room floor on black construction poly sheet in full sun from the North. I moved indoors as leaving them outside meant that any reaction would cease in the cold of night. The room temp is 21c or 70f and its only 11am here so it will get warmer and less cold at night. The panels them selves are much warmer than 21c - but I don't have the means to measure the temp. Today is gorgeous, blue, cloudless sky and tomorrow even warmer 24c but then it returns to 20c (ish) - so I'm hoping that all your advice can be applied today and tomorrow.

You'd a bit of sympathy until you posted those numbers Jonathan......

In my defence - that's one reason for living here - we (or I) was promised BBQs beaches and bikinis and the unusual cold this year (and the complaints of some of the heat in Europe) - meant I was questioning my reasoning. This is an unusual warm 2 or 3 days - but this heat does not penetrate my workshop (nor remain in my bones once the heat reduces).

But it does give us a 365 sailing season

Jonathan

 

[penfold]

Make a hot box; put a hair drier inside if you don't have anything else. If the unset portions do not set in 40-50C they aren't going to.

 

[iamtjc]

West Systems epoxy somewhat crystallises in the cold. You can restore it by warming and stirring (stand the can in warm water). I stored a new can in a temperature controlled box over winter to avoid it freezing. The box was a constant 11C and even so there was some crystallisation in the spring. Whether the crystallisation affects the properties of the remainder of the epoxy I haven't tested but intuitively it seems like a good idea to make sure the resin is fully liquid before using it when it has been cooled.

 

[rogerthebodger]

Make a hot box; put a hair drier inside if you don't have anything else. If the unset portions do not set in 40-50C they aren't going to.

Or make a solar oven to cook the GRP.

I had a similar issue some years ago and put te in SWMBO's oven as 100 C overnight and it cured OK.

You need to get the temperature up to cure with out internal heat

 

[Neeves]

The sun and the increase in temperature between my workshop and the lounge room has done the trick. The 2 units remained on their black polythene backing and I simply moved them around (wooden floor) as the sun traversed the sky. The tackiness has all gone and the units are firmer and less floppy. By tomorrow it should be hard enough to sand.

I simply used the heat from the sun through the windows beating down on the 2 units for a few hours each day and the higher room temperature of 17-20c over 3-4 days and that has done the trick. None of this is relevant if you have a schedule, lack patience (or the piece is too big to get through the door).

Thank you all for the advice (which also provided much moral support)

Jonathan

 

[tilly56]

Warming off your workshop is the only option and lay the 2nd coat

 

[tilly56]

Warming off your workshop is the only option and lay the 2nd coat

if you can provide a UV light it will be helpfull and also check the quality of the resin