Epoxy second layers - the solution

Discussion in 'Boatbuilding' started by Manie B, Nov 29, 2008.

  1. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

    This has been a lot of hard work

    but the solution is simple and easy and FAST and cheap

    wash with dishwashing soap - sand - wipe with vinegar

    WHY ??

    first lesson - what is known as Denatured alcohol in other parts of the world we call Methelated spirits = purple - our homeless people filter it through bread and then drink it with coke - only available from pharmacies and expensive - will cause blindness

    for some reason BOTH DONT WORK

    i work with two types of epoxy a 2:1 mix and from another supplier a 5:1 mix, both work well but both give a blush

    the 2:1 is nice and thick with a consistency of syrup or honey - slow curing and very nice to build / glue with and makes a great putty mixed with equal portions of cotton flocks and cab-o-sil

    the 5:1 is very watery and is fantastic for wetting out glass and coating / painting large plywood surfaces - the first coat goes on nice and thin with a scraper - easy to sand down

    "peelply' works well on large flat surafces - but when you want to "paint" in tight corners - or if you just havent got the time to go wet on wet - or if you have a small bit of epoxy left over - even repair work

    YOU MUST BE ABLE TO SCRUB afterwards to ensure that subsequent layers of epoxy stick well

    firstly i give a light wash with a pot scourer - cloth and dishwash soap and water
    then my little sander came with a "scouring" pad that works like a bomb - scrubbing is easy now
    then wash again with the soapy water and rinse well with a cloth dipped in CLEAN water 2 times

    SAND WELL - 60 grit paper works well for me

    now the easy part - WIPE DOWN WELL with a solution of 1part vinegar and two parts water (our household vinegar is only 5%) let it dry

    when dry it leaves a very slight film of white powder (almost unnoticeable) on the surface - i am not sure if this is the vinegar or our crappy water - but i wiped it clean with toilet paper

    WHY ??

    soap is an alkaline
    vinegar is acidic

    it is important NOT to have a alkaline surface
    believe me i have gone thru enough **** this week
    and tried many many things
    i am convinced that
    THE SURFACE MUST BE ACIDIC

    love to know what the experts have to say about this one

    anyway you can see that i got so flippen mad that i even have separate gloves for specific usage

    i read wikipeadia and the very good forum on bateau

    http://forums.bateau2.com/viewforum.php?f=4&sid=efe7a525ae1b1f040bcf5e753bebb89e

    all very good information

    so here are the pics

    my "shine" of 3 layers epoxy and 5 layers of varnish is actually achievable AND i know that when i build and work on my CAT my second layers have got GOOD ADHESION and i dont waste epoxy because i can paint it on my big boat in open spots

    this has been a very valuable exercise

    if at first you dont succeed - try agiain :D :D :D
     

    Attached Files:

  2. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

    oh i forgot

    i rolled the epoxy out with a regular sponge roller
    and then just "tipped" the air bubbles out with the paint brush

    all very easy and fast
     
  3. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    Hey Manie, I'm glad you could get your problem sorted out too.
     
  4. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

    Some more info as i remember them

    during this weeks research there is a rather common thread that does come thru - it seems like in first world countries you can get very smart epoxies that have no blush, but are very toxic and emit heavy fumes

    the stuff i get here are no/low fumes, easy to work with, and so far no skin irritations and/or side effects

    BUT it does have blush, but it is easy and fast to clean off

    this is the watery epoxy that i have no problems with

    so the idea that comes to mind is that maybe too smart is not so clever at all - just thinking out loud :D

    http://www.amtcomposites.co.za/data_sheets/SP_106_TDS.pdf

    http://www.amtcomposites.co.za/index.html
     
  5. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    I disagree. You can get in SA what you get in other countries. Other countries doesn't have this f plague we have here that is stupid and arrogant and fcuks everything up in their path. In other coutries the people that handle stuff have a tendency to treat the stuff you bought (other people's stuff) with respect. I cannot tell you how many times I have received goods that was ****** up before I could receive it. Other than that, SA could be a leading first class country.
     
  6. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

  7. Jimbo1490
    Joined: Jun 2005
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    Location: Orlando, FL

    Jimbo1490 Senior Member

    I've never heard of the need for an acidic surface. I'm not discounting this, I've just never heard of this before now. The soap and water scrub is considered the best way to remove the amine carbonate salts that deposit on the surface as 'amine blush'; the alcohol wipe is just for final cleaning before bonding. But sanding is a good idea if the resin has cured fully, which in your climate it certainly will have in 24 hours.

    I forgot that 'denatured alcohol' is banned in many places. Most people have the good sense not to drink the stuff since it's poisonous. Here they take cold and allergy medicine and turn it into a highly addictive drug, so now it's become regulated and hard to source where it used to be a non-regulated domestic medicine like aspirin.

    Jimbo
     
  8. Roly
    Joined: Jul 2005
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    Location: NZ

    Roly Senior Member

    West doesn't seem to blush here so only have to sand.
    Must remember to try vinegar tho'.
    We use it for 1st wash of brushes to save acetone.
    Turns the acetone cloudy. Must be some kind of precipitation?
    Good trick to know...thanks for the research Manie.

    You must spread a little around before you...............geez, boring bit of dialog that.
    Musta been a long time ago, 'cos I don't remember it.

    Edit again I must be goin a bit senile.
    West DOES blush from time to time ( or is hard to sand anyway)
    When I need a bit more elasticity in th epoxy I don't use the full 1 part of hardner (5:1 mix) (Like 5.5:1)
    and it is a whole lot less brittle. Used It on the engine beds where th laminate is thick hoping for a bit of extra damping.
    Whatya think?
     
  9. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

    The reason why i refered to the acidic surface is because some folks on Beateau tried a pool acid solution and it worked

    In one of my experiments i wiped a "vinegar surface" with alchohol / meths and back to square one = no adhesion

    back to vinegar and bingo - all good

    what struck me was the absolute simplicity of it all
    dishwash soap wash - clean water rinse - sand - vinegar wipe - next coat of epoxy

    clean brushes with undiluted vinegar and final wash with soap

    my next experiments will be PU varnish and white enamel paint

    one of my beeeeg problems initially was fear of the unknown - i had read so many horror stories on epoxy that i was loath to work with it in my garage at home, i dont want to create an image of over simplicity and /or carelessness but i do want to encourage people to build - its not that difficult.
     

  10. AndrewK
    Joined: Mar 2007
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    Location: Australia

    AndrewK Senior Member

    Manie

    Vinegar is good for cleaning epoxy, I only use it to clean epoxy of my skin but prefer acetone for equipment.
    Water is all you need to wash off amine blush.
    Vinegar being an acid will react with the amine (base) to form salts, this is the white powder left behind after drying. If all of the amine was washed off in the first place then you would not get any salts after vinegar wipe.
    You say that if you follow up the vinegar wipe with metho the problem comes back, then I would suspect that it is the metho or rags used to wipe that is part of your problem.

    Regards
    Andrew
     
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