Pouring Spartite/PCM790 OK at low temperatures?

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  • 16 Jun 2018 22:17
    Reply # 6316355 on 6152925

    David, Graeme,

    David I forgot to mention the hot water bottles! That was a great idea. I took 7 to the boat (we had a load of visitors in a cold spell a while back!) arriving at about 23:00 and immediately filling the bottles, packing them round the step as best I could and covering them with jackets and other insulation. In the boat it was about 9deg C I think. I didn't have great hope. But at 04:00 (refilling bottles) the thermometer buried with its bulb at the bottom of the cavity between mast and step socket was 12deg C! By 07:00 it was almost 16, the recommended minimum being 18. But how to keep it there for 48 hours?In the end due to other circumstances I decided to put the boat in the canal basin  where there was power, and not leave her on the swinging mooring. A convection heater did the job. But I'll remember the bottles in future. It did surprise me that they heated that mass of built-up ply and epoxy and to that extent, despite the cold sea temperature and heat-sapping keel!

    It was great to get the forecabin up to 23deg with the gunk stored in there ready for use. It is important that the gunk is warm as well as the step .

    Graeme thanks for sharing your trials with us in the post which you mention below - easy tabernacle - but which I can't see as I write this... It is so easy to be affected by "the heat of the moment" doing these jobs. In my case there is often more madness than method, and I've paid the price because of it more than once during this conversion, when working with epoxy, usually long into the night! But despite the cause of your trouble remaining a mystery, I'm glad to hear it worked out in the end.

    Pol


  • 30 May 2018 10:45
    Reply # 6272812 on 6152925

    Pol had already done the pour at the heel, and it looked very good to me.

  • 27 May 2018 13:24
    Reply # 6266441 on 6152925

    Pol I hope all went well with your urethane pour. You are lucky to have had David there to supervise. I have a further failure to report, which I would like to make known. It may have been my fault, anyway if David wants to know about it, I have put it on the "Easy" mast stepping - alternatives for a tabernacle? thread.

    Last modified: 27 May 2018 13:41 | Anonymous member
  • 17 May 2018 15:39
    Reply # 6239453 on 6152925

    I think a release agent is important, and I guess you are OK with grease, imagine if there were any potential chemical problem with grease the product would carry a warning. If you can’t reach everywhere with grease, the expensive spray-on stuff might do it as it is a fine mist, like CRC and would drift into those hard-to-reach places. Come to think of it, CRC might even be just as good. As with grease, first just make sure no chemical issues. Did you say you had a couple of test pots?

    I am not too sure about the polyprop codline. Whether urethane would adhere to it or not, I don’t know – but depending on how you deployed the codline, beware of mechanical interlocking, that would give this stuff a pretty good grip. 

    Down here in the southern hemisphere, when there is nothing much else you can do, we say: "She'll be right!" 

    But better you check these matters out with David.


    Last modified: 17 May 2018 16:30 | Anonymous member
  • 17 May 2018 11:48
    Reply # 6239053 on 6152925

    Thank you very much, Graeme. I will have a look your write-up with interest. Especially how you allowed for the vacuum to be broken at 'mast out' time. In my high excitement at getting the mast stepped I forgot to do that which might be serious.. But I've managed to get some greased polyprop 'codline' down there and packed round the heel with Plasticine. And there'll be lots of grease in the right places before pouring.

    Pol.

  • 15 May 2018 11:30
    Reply # 6192343 on 6152925

    I have just finished pouring a similar product and have some feedback for David on the subject - but nervous now about which thread I should use! 

    Pol, and David, if you are interested, I have written up the results in the thread called "Easy Mast stepping? Alternatives for a tabernacle".

    Last modified: 15 May 2018 11:30 | Anonymous member
  • 15 May 2018 00:27
    Reply # 6176610 on 6152925

    Thanks, David,

    Already it is looking warmer over there next week so that bodes well - for both of us! I am sure you are right doing the warm-up of the containers for some time before mixing and pouring will help. And also hot water botts piled up around it could keep it that way for long enough. I'll bring the stuff back with me this week and give it a test - it ought to last a week after opening and re-sealing carefully. I got two 'trial packs'.

    Great that you are going to be up with Weaverbird. Extremely kind offers of help! I will send a PM as soon as I know my plans for next week.

    Have a great sail.

    Pol.

  • 14 May 2018 13:20
    Reply # 6158823 on 6152925

    Thinking of ways to raise the temperature:

    When epoxy is too sluggish to pour and mix, it helps to put both containers into a warm water bath at the upper end of the recommended working temperature. This method should work here, to get through the initial setting time of 20 minutes. That should get the cure well under way. After that, a hot water bottle or two, covered by a blanket, would get you further down the track, and the final part of the cure will happen later in the summer when (if?) the water warms up.

    I wasn't thinking of the weekend, it will take me a day or so to sail down to Crinan. Let me know by PM when you'll be bringing the sail, and I can maybe help with the carrying and rigging.

    Last modified: 14 May 2018 13:21 | Anonymous member
  • 14 May 2018 12:19
    Reply # 6156794 on 6152925

    Hi David,

    Thanks for your reply. All indications are that, as I suspected, the correct temperature should be stuck to. It is almost as much to do with humidity as it is to do with temperature. I spoke to Bentley Materials who supplied me with the PMC790, who suggest trying a small bit to see how it goes. The risks at lower-than-recommended temperatures are that it forms more bubbles than it should (which would not bother me too much as long as it wasn't frothing up and weaker as a result) or it simply does not cure. I'll try a test bit this week and see how it goes. If I have to move in to the Crinan canal basin for 2/3 days to get heat and a calm berth, so be it.

    We live about 3 hours from the boat. I'm really sorry to say that I won't be over there at the weekend - something that I can't get out of I'm afraid!  It would have been great to meet you and I would very much like to have shown you the boat and the job so far.

    I hope to take the sail over there next week for the exciting bit!

    All the best, and have a good meet at Craobh,

    Pol.

  • 14 May 2018 07:00
    Reply # 6153140 on 6152925

    Hi Pol,

    I think it would be advisable to use the tech online support form:

    https://www.smooth-on.com/support/ticket/add/agree/

    I'll be at Croabh Haven 19/20th, for an OCC gathering- may I come on down to Crinan after that, to see how you're getting on?

    Last modified: 14 May 2018 07:43 | Anonymous member
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