Cobalt in resin.

very interesteing, thank tunnels> I have not been using it and as you say for a newbie with loads of time Im getting 12 hours hard time in 90 degrees. This gives me a wet surface the next day to continue laying up (only 3) probably better for me to keep it that way.

 

G'day 'Frosty-cone' - "very interesting, thank tunnels" yea - right - but not all that correct. There is far more to it than what has been said & some of the whole story may well be a tad misleading - me thinks.

Your - 'wet-face' may have something to do with other activities & could be a lot of fun with the right company - I'm sure of that!! Save some of those activities for when we have some 'sundowners' - hey mate - please - please.

The 'wet surface' - meaning still tacky (?) is a product of whether the polyester resin has a wax additive added to it or not. Wax free - leaves the surface exposed to the air - sticky to touch (caused by the surface being exposed to the air & inhibiting the surface cure) which is why it is used - that is - so one can go back to laying up on it at a later date & getting as good a mechanical/chemical bond as is possible. A pre waxed resin - will be not sticky & thus be easy to sand - but must be sanded - or subsequent applications of laminate will not adhere properly. IMHO ha ha. Hay cobber - have a great day - don't hold your breath - but I will get there. Ciao, james

 

Frosty there are better chemicals to use than cobalt !! best thing you can do is to be-friend a chemist in a resin company !!

The polyester resin used in New ZEaland is cool ! its been designed specially with boats and the huge long list of problem associated .
The french guy that started making the resins was very clever and worked with his own resin !! so he understood what was required so made and used and has never been bettered since !
Starts it life blue then , turns green when you catalyse it , turns yellowish when you are using and lasts like that till just before it gells and then goes grayish . colour coded !!
There only need for just 2 differant catalysts strong for the winter weaker for the summer ., Exotherm never gets to hot but will maintain its warmth
It has a long gel time !so plenty of work time ,a good cure time .

Here in China the guys on the floor were loading cobalt to all the resin they used all year round !! summer and winter !!
The shrinkage and problems were mind boggling .
I asked why isnt the resin pre-promoted ?? A phone call to the resin supplyer and yes it is promoted already !!
Now no more cobalt gets used except in the middle of winter ! so the problems are less than a 1/4 of what they were before and just have to work on the last 1/4 !!.

 

I guess the NZ resin just had a blue indicator added. Which over here is pretty normal.

You also can order MEKP with a red indicator. Will either fade during cure (Europeans like that) or will not fade (Americans like that)

 

Hi
The colour codeing for the differant stages was something perfected over a period of time and we have all grown up with it and makes life really simple dont need red dye for the catalyst !! pre the colour code i used red dye in the catalyst when i used a saturator gun to get a slightly less resin rich lay up i learned to use a little more dye so it looked wetter than it really was . worth thinking about .
I tried to get red dyed catayst here in china but they didnt put much dye in so was a wasted effort . Had a problem with a chopper gun and dead resin before anyone noticed there wasnt any catalyst . so colour coded resin could have picked up the problem immediatly or the use of dye ! either one . the dye only shows catalyst, the colour code shows catalysed and at what stage the resin is at as it changes from green to Yellow and then to light Gray .
Interesting i came across white gelcoat in Australia that had a pink look about it when it was catalysed once gelled it changed back to white ! never come acoss it any where else .

 

Thanks for that tunnels , that is the most valuable information I have had for a long time . Adding cobalt --say 5 % really gets things going on fillers. Before I could get fillers not going off, now I cant get it to go off withing 5 minutes and start fairing. I have a much better understanding.

Rep points coming,--when I am allowed. I wish I could give you some now -you deserve it. Information nothing to you but life changing for me thats what the forum is for.

 

Using polyester and Vinylester resins !!
Making FILLERS and FAIRING etc !!
We had differant recipies for differant mixes .

FILLERS but able to stick well ! just used Talc and aerosill 50/50 by volumn !! not light weight but stucks well , if 5 mm thickness add some microfibres so its less likely to crack as it hardens and with age .

FAIRING use a small amount of Talc and aerosill but more Qcells or microballoons !!The more micro balloons the easyer to sand but will be brittle so carefull where and how much you use !! Plus keep a eye on the stickablility as its looses its stick and could simply fall off with a little knock so any place where theres vibration or panel flexing careful .
There are flexable resins that can be used for panels with movment ! Use less Qcells and a little more aerosill ,
Aerosill with thicken resin ! Q cells make it easy to sand , talc give a little strength and also thickens but harder to sand Micro fibres is good to help hold the mixes together and give some guts specially where there is thickness involved !
Using any of there in any quantity will naturally dilute the resin so add a little Cobalt to bring back the gel time BUT LIKE ALL THINGS MODERATION AND DONT OVER DO IT !!heat cause shrinkage and shrinkage will distort and pull and if the pull is to great then it could shrink off the surface its stuck to . !! Its a chain reaction !!!

 

Again all great help but shrinkage--- if its shrinkage around a pipe say--then It will be tighter No?

I have very few materials available, I have simple little Hardware shops that sells polyester resin , they call it 'epoxy' and give you a bit of hardener, they dont even know what it is. When I come down from Thailand I can buy matting and cobalt and proper epoxy and talc.

It about as technical as I want it to get for my little faring and filling jobs.

PS faring the pipes is the biggest job. I cut half a plastic bottle to apply the filler and has worked well.

 

Tighten to the point where it will break at the weakest point !! so add csm to the mix and wrap it around the pipe .