epoxy paint filler additives

Discussion in 'Materials' started by valvebounce, Jun 21, 2012.

  1. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    I am about to purchase some epoxy two part paint and was wondering if it is possible to add a filler powder of some kind to fill low spots before painting,and maybe add fibreglass chopped strands for bigger areas.
    I am about to glass in some stringers that have been replaced using chopped strand mat,could I use this paint to wet out the glass on the stringers ? I believe when using polyester resin it can sometimes fail to adhere when applied to fibreglass hulls.My hull interior has been painted by a previous owner with what I suspect is oil based paint,this is making the job more difficult trying to remove it.The hull is only 8mm thick,so abraiding it with power tools is likely to cut through it.Would a conventional paint stripper/remover damage the fibreglass?
    Any advice will be gladly accepted and appreciated.
    The epoxy paint is aircraft quality
     
  2. gonzo
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    gonzo Senior Member

    Laminating resin and paint are not the same. For a structural repair you should use laminating resin. Power tools can be used in even thinner hulls than 8mm. If you have some kind of unknown coating, there are several ways to remove it. A chemical stripper is an option. I like sandblasting when possible; it takes the coatings off and abrades the surface so there is no need to sand or grind.
     
  3. pauloman
    Joined: Jun 2010
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    pauloman Epoxy Vendor

    gonzo is wrong. The primary difference is pigments and thixotrophic additives in the paint vs the raw resin/curing agents used for laminating

    --- Paul Oman MS MBA ---
    Member: NACE & SSPC (National Assoc. of Corrosion Engineers& Soc. of Protective Coatings)
    ----------------
    Progressive Epoxy Polymers, Inc.
    info@epoxyproducts.com
    -- www.epoxyproducts.com/marine.html -- also -- www.epoxyUSA.com
     
  4. mastcolin
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    mastcolin Senior Member

    Let's not yet again get into pseudochemistry discussions here.

    It always amuses me that people try to reinvent the wheel. I am all for out of the box thinking but you should really ask yourself if you are so smart that you will beat technologies that make aircraft parts...or paint aircraft.

    1) the oil based paint may possibly removed by a gentle paint stripper ie one that will not eat into the polyester. Go to shop and read the labels carefully. Very carefully. Boatshops stock polyester safe strippers...it may take a few applications though and you may need to get busy with scotchbrite to help it.

    2) your epoxy primer is made for thin films. If you add filler powders you will make all sorts of problems for yourself eg you will entrap solvent in the "fillerpaint"and then you will have problems. Buy a proper filler. Sorry. There is no sortcut. We apply 10 x thousands of litres of filler. If there were cheaper/better options we'd know about them.

    3) don't laminate with paint, even solventfree paints. The paint is designed to be paint, laminating resins are designed to be laminating resins.

    If you want to track race, but a 1seat car. If you want to take wife, kids and dogs on holiday, buy a car with enough seats and luggage space. if you want to transport dirt, buy a truck. They all have 4wheels, brakes, streeing wheel etc. They are all designed for their purpose. You could use the truck to race against real race cars...you'll just finish last. You get my point?
     
  5. sabahcat
    Joined: Dec 2008
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    sabahcat Senior Member

    Use epoxy resins and fillers for major fill
    But I have added Qcell to epoxy primer before to make a spray bog
    Once faired, use unadulterated primer for final
     
  6. valvebounce
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    valvebounce Senior Member

    Many thanks gentlemen,I can see there are no shortcuts or more economic ways of doing the job.Sticking to tried and tested methods is obviously the answer.
    I'll try the paint stripper like you suggest Colin.
     
  7. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    Paints are already filled with color, if you had filler material it will be weak.
     
  8. valvebounce
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    valvebounce Senior Member

    many thanks for the advise
     
  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Paul is correct, most epoxy primers have fillers in them already and even top coats have some levels of fillers in suspension, if for no other reason than to bulk up the film.

    As has been pointed out, you'd be best off using the appropriate product, though from a technical stand point you could add a level of filler to both primer and top coat paints, though their value may be dubious and adhesion could be affected.

    Simply put, if you have some shallow imperfections, pin holes and scratches to fill, use a building primer and knock it down smooth, then top coat as desired. If you add say talc and/or silica to the top coat, you can expect it will dramatically effect the gloss and likely surface adhesion, of course dependent on filler content. Rather than take a guess at how much and if it'll stay stuck once applied, the wise decision is to bulk it out with primer, complete the surface prep and top coat normally.
     
  10. pauloman
    Joined: Jun 2010
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    pauloman Epoxy Vendor

    generally epoxy primers are nothing but solvent thinned epoxies. Most 98%?) of epoxy paints these days are solvent free (0% VOC) as are the 'marine epoxies

    solvents added to epoxies 1) thin the product, 2) reduce the physical properties of the epoxy, 3) add flex, 4) extend pot life.

    most epoxy formulators are OK with adding up to about 10% solvent (to the part A).

    Solvent free epoxy coatings/ paints and solvent raw resin - marine epoxies are very similar with just a few extra things added to the epoxy paints the most obvious being pigments.

    the concept of a laminating epoxy vs other kinds of epoxy is, in a general sense, mostly marketing - sort of like men's perfume vs women's perfume - or breakfast tea vs regular tea....

    In simple terms epoxies are a group of chemicals that when they interact with each other produce a semi hard solid. How that reaction is used, modified or applied is all marketing to develop profit making niches from the results of a simple chemical reaction. It is not rocket science, just chemistry and marketing.

    paul oman - owner
    progressive epoxy polymers inc.
     
  11. valvebounce
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    valvebounce Senior Member

    Thanks PAR,I'm glad you are keeping your eye on me,this boat thing is a new learning curve for me,and your logic is a big help.
     
  12. valvebounce
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    valvebounce Senior Member

    Hi Paul,looks like the tried and tested route is the only way to go,I'd hate to get the job finished and then have it fail.I'm in the dark when it comes to the chemistry,so Im obviously stuck with the marketing guidelines.
    Your input is much appreciated,thanks once again.V.
     
  13. mydauphin
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    mydauphin Senior Member

    I have a philosophy on my boats, I only use the good stuff underwater. Above the water, I will play will mixes and old epoxies. If I have to remove them or they crack it is not the end of the world. It seems the heat of the sun can be very damaging to certain epoxies. Yes, even thou painted they shrink and crack.
     
  14. Angélique
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    Angélique aka Angel (only by name)

    That seems to introduce some of the disadvantages of polyester if I interpret Dudley Dix's FAQ well . . . :confused:

    FAQ - Wooden Boats
    Red paragraph lines in quote inserted to make it easier to find it on the linked page and read it in original context.

    Cheers,
    Angel
     

  15. bntii
    Joined: Jun 2006
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    bntii Senior Member

    Sure- you still can't use epoxy paint as a substitute for laminating resin.

    They different products suited to different uses- they are designed as such for function not "profit making niches"..
     
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