Cobalt in resin.

Discussion in 'Fiberglass and Composite Boat Building' started by Frosty, Jan 23, 2012.

  1. Frosty

    Frosty Previous Member

    What is cobalt ? Im encouraged to use it by my little resin shop . I think he is telling me to use it to make it harder and not tacky. He suggests a tiny amount.

    What is it and do you use it.
     
  2. hoytedow
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  3. Frosty

    Frosty Previous Member

    Really ? this was on your link.

    Cobalt is the active center of coenzymes called cobalamins, the most common example of which is vitamin B12. As such it is an essential trace dietary mineral for all animals.

    It is also used in beer--it goes on to say.

    Nothing however on using it in Polyester resin!!
     
  4. hoytedow
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  5. hoytedow
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  6. pauloman
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  7. dinoa
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    dinoa Senior Member

    Cobalt napthanate is often used to accelerate the curing of polyester and vinyl ester resins.

    Dino
     
  8. Frosty

    Frosty Previous Member

    Is it necessary ?--what if it is not used? is there a particular application where it has to be used.

    What is the benefit of using it for a small user like me on DIY projects where I will mix nothing more than a coffee cup at a time.
     
  9. FMS
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    FMS Senior Member

  10. Frosty

    Frosty Previous Member

    Have it mixed to my specifications? I only buy a liter at a time at the hardware shop. In Malaysia they dont know what it is -In Thailand they sell it to you everytime in a tiny plastic bag along with a similar packaged hardener.

    I am told-- a small drop is sufficient for a coffee cup full 0.1%,- the hardener at 1 %, I am following the instructions successfully but have no idea why

    In the temps I am working in you only need to wave the hardener over the resin and it will go off.
     
  11. Silver Raven
    Joined: Oct 2011
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    Silver Raven Senior Member

    The use of 'Cobalt'

    'To 'Cobalt' or or Not to Cobalt - that is what ?.

    With all 'polyester resins' - what is called 'catalyst' is just that - a substance that increases the rate of a chemical reaction without itself suffering any permanent chemical change - dictionary. Catalyst can come in several different strengths. Catalyst 'starts' the action of the resin going hard - roughly speaking - Cobalt - will - accelerate that action.

    Ideally speaking - you don't want the resin to 'gel' before it has had time to - wet out all the fibers of the reimforcement being used. THIS IS VERY IMPORTANT As your are well aware - least is best - everywhere in the tropics (hell man - I've only lived here in Cairns for 30 years or so) - been in the FRP industry - building yachts - since '54. Try to keep catalyst somewhere above 1/2% if possible - best is 1% - (MUST be mixed in very well - for obtaining the best results) then if you need to shorten the 'gel' time use 1/16 - 1/8 or so % cobalt - - VERY very little - use a little eye-dropper - is the go.

    You may wish to refer to - "masalai's comment" - from SEQ - OZ - 'post' #4344 - 23rd jan - 1654 hrs - "Your helper might be able t" - - if that doesn't work try me - PM - not anything personal!! HE he he he he. Ciao, james

    I really wish I was up ther to help - just to show - my thanks for your info about the place - but t'ther's to many bloody Aussies here already' hey!!

    Do PM me if you get in bother. Ciao, james
     
  12. keith66
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    keith66 Senior Member

    Cobalt accelerator is added to resin to allow the catalyst to set the stuff.
    Most resin in the UK is now supplied pre accelerated so you dont have have to add it yourself. This is a very good thing as, a) its toxic & b) if accelerator comes into direct contact with peroxide catalyst there is a violent reaction that is liable to be explosive.
    I remember at Thames marine years ago when someone put Catalyst in a Cobalt dispenser by mistake it reacted & he threw the dispenser, it went of with a large bang & left some interesting stains on the walls. Fortunately no splashes in anyones eyes.
    Only normal use would be to add more to aid setting in very cold conditions.
    In Thailand i wouldnt see any use for it at all unless the resin is supplied un accelerated, which may be the case to extend shelf life?
     
  13. Frosty

    Frosty Previous Member

    Thanks Silver and Kieth that just about hits the nail on the head, I understand now what it is.

    I think Thailand must supply un accelerated because one shop said it was already mixed in, he does it himself after de canting from a 50 gall drum into water bottle type containers for small 1 kilo purchases.

    I might as well drop a bit in now ive got it.
     
  14. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    Some types of resins (VE and filled resins) are commonly supplied unpromoted because they tend to have poor stability and the shelf life is fairly short. And in some parts of the world it's more common for them to come unpromoted because this gives the end user more adjustability when there are fewer resin choices, it also extends the shelf life in hot regions or where usage may be slow.

    In the US and some other parts of the world if you want a 12 minute gel time you can buy it, or maybe 15, 20, 25, or 35 minute, they can be found easily. But if the demand for product doesn’t justify stocking all these different gel times, the distributor may stock an unpromoted version, or the 35 minute product and have the fabricator add a small amount of cobalt and/or DMA to speed it up if needed.

    Cobalt will affect the gel time and DMA will have more of an affect on the gel to peak (the time from when it gels to when it actually cures and becomes hard and reaches it’s highest temperature)
     

  15. tunnels

    tunnels Previous Member

    Cobalt !All the time i have worked with resins and glass early every company has Cobalt and use it for a few differant things. One company they used acetone and cobalt mixed to brush onto wood and let it soak in and then resin and glass over when using polyester and Vinylester resins . seemed to be ok ! dont know about the long term !!

    When making surry , fillers and fairing always mix cobalt ! everything you add to resin slows it down so the cobalt will speed it back up , Like all things to do with resin dont go overboard and get carried away !!! add to much and you end up cooking things with the excess heat thats produced . Heat = shrinkage = pre release = distortion !!!

    Moderation is the name of the game , specially for those that are newbies !.

    CATALYST AND COBALT ARE INSTANT HEAT AND SMOKE AND FIRE !!!
    SO be warned !! if you are working at home and at work keep COBALT AND CATALYST separatored like at differant ends of the building !!! . if you have never seen a fibreglass place burn you are in for a treat !! takes a little effort to get the resin started to burn but the heat is so intence and all you have time to do is run . the smoke and fumes will kill you !! also if working at home keep them away from and completely out of the reach of children of any age including mindless thoughtless teen ages !!:confused::D;):p:)
     
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