ZEP floor polish as an acrylic conformal coating

Discussion in 'General Electronics Chat' started by sdowney717, Mar 23, 2015.

  1. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    ZEP is a water based acrylic coating. People use it on floors. Home Depot sell this as a gallon container for $20.
    I have been using it for other reasons. I have coated wood. It gives the wood a waterproof clear finish. Water beads up, does not dissolve the Zep coating.
    It dries fast within 15 minutes. It gives the surface a semi gloss look. On wood I use anywhere from 2 to 4 coats with a full dry in between coats. New coats slightly dissolve into earlier coats. Ammonia is a solvent after it is dry.
    I have coated plastic and metal and am impressed with how it sticks.
    I refinished my stained wood desk and it is holding up well.
    Other people have used it outside on painted surfaces or to keep metal from rusting.
    I put a piece of Zep coated wood in the oven at 170*F and the finish remained as it was, did not get sticky or come off.

    So for all the durability reasons, I was thinking what about coating circuit boards with Zep?
    Paint it on using a chip brush?
    Do people coat both sides of a board or just the solder side?
    When you read or hear of people using acrylic coatings on circuit boards, what are they using?

    For example here is Zep floor polish on a wood board.
    [​IMG]
     
  2. Brevor

    Active Member

    Apr 9, 2011
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    We have used Zep products where I work, they are good products. I say go ahead and use it to coat your boards, I dont think it would hurt anything.
     
  3. Reloadron

    Active Member

    Jan 15, 2015
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    You may want to read this link.

    If the Zep meets enough of that criteria to suit your needs than give it a try. Long as it dries with good insulating properties and is non-conductive.

    Ron
     
  4. #12

    Expert

    Nov 30, 2010
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    Coat all of the board to prevent humidity from interfering.
    I have fixed many a QC problem with a hair dryer.;)
     
  5. WBahn

    Moderator

    Mar 31, 2012
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    The things I would worry about are:

    1) It's ability to allow heat to get out of the components and into the air.
    2) It's ability to withstand the heat generated by the components.
    3) The likelihood of fire or toxic fumes if it gets too hot.

    You can probably do some simple tests to see if these are big issues. Also, looking at the warning labels on the product, particularly regarding fire and toxicity, might be useful.
     
  6. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    Zep acrylic floor polish is a thin water like consistency. It is a bluish white but dries crystal clear.
    So far I like how it works. Reminds me of Minwax water based polyurethane, but a lot cheaper by the gallon.
    It is dissolved by ammonia, so could be stripped off by using ammonia.
    Dried coating is flexible. It does not crack. It is supposed to go on floors and stand up to foot traffic so durable.
    It has some ammonia in it so that recoats melt into the prior coat, so good bonds form between coats.
    I tested it on wood at 170*F in the oven and the coating was not affected. How hot are those conformal coating designed to handle?

    I refinished my wood desk with Zep and it has a great surface finish. I run my mouse over it now for a month and no wear.

    My finish process was, I first sanded with 120 grit random orbit, then used some oxalic acid to clean and brighten the oak wood, then stained with Minwax Ipswitch pine. Let it dry for 3 days, then coated on 3 coats of Zep.
     
    Last edited: Mar 23, 2015
  7. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    Re: Suitability criteria for 'off-label' use of substances as lacquers applied to electronic assemblies...

    To the requisite characteristics stated above I would add: 'acceptable dielectric properties' --- A simple (and, in many cases, adequate) test may be realized via placement of a 'pellet' of dried lacquer upon a piece of 'solid' paraffin (a.k.a. 'paraffin wax' --- e.g. n-eicosane) in a 'microwave' cooker then watching for signs of heating (i.e. 'fusing' of the paraffin) and/or deterioration of the prospective lacquer...

    Of course any material exhibiting a suitably low GTT and high degree of 'RF lucency' may be substituted for the 'paraffin'...

    Disclaimer: Please be attentive to the facts that this test is rather 'coarse' and tightly 'monochromatic' (test signal λ~122mm)

    Best regards
    HP
     
    Last edited: Mar 23, 2015
  8. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    The goal of conformal coatings is to prevent moisture from damaging components and preventing oxidation of the copper traces. ZEP is essentially a latex paint (also known as acrylic dispersion). Instead of a thick white coating, it us clear because there is no titanium dioxide base white pigment. Unlike a solvent-based acrylic paint, the water-based material has dissolved salts (sodium meta bisulfite, sodium chloride, ammonium chloride ). It will likely conduct slightly until completely dry and may start conducting (microAmp) again in high humidity. The degree of problems will depend on the circuit and low current requirements.

    The biggest issue is that latex paint can be corrosive - depending on the specific formulation. The sodium chloride and ammonium salts do not play well with copper. Look for malachite green edges on the traces over the next weeks.
     
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  9. #12

    Expert

    Nov 30, 2010
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    Lovely to have a chemist on board!

    I actually can't understand the post by HP but I did my water conductivity test like this: Create a chunk of the suspect material, put in in your pants pocket, and run your pants through the clothes washer. After the spin cycle, wipe it dry and measure its ohms.
     
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    ..... and if your pants have dissolved, reject the stuff as unsuitable for conformal coating :).
     
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  11. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    Maybe a good test would be to coat the backside circuit board of an old hard drive and then leave it running for a couple weeks in a desktop computer?
    They have a lot of tiny and I would think sensitive components on the board.
    And I have enough old ones I don't mind destroying for the sake of a test.

    I could even with a running coated board lay a wet sponge on and see what happens
     
  12. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    Sounds like a plan:)
    Be aware, however, that 'electrically compromised' HDD logic could, conceivably, damage the controller and, perhaps, the mainboard...

    Really though... Why 'sweat the contingencies'? -- Commercial 'on label' electronics lacquers don't cost that much...:cool:

    Best regards
    HP
     
    Last edited: Mar 24, 2015
  13. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    That assumes there is no conformal coating on the hard drive already. Likely difficult to find a hard drive without a conformal coating. You need the product to come into contact with the bare copper.
     
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  14. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    Ok, here is the test subject, an old Maxtor drive with lots of exposed circuit components.
    I posted a 7:56 am and I am now running with the coated board, shows how quick to dry.
    I simply painted Zep on with a chip brush.
    I also after it was mostly dry placed in front of a small heater.

    I plugged it into the USB and it works on the computer.

    wet Zep board
    [​IMG]

    Dry Zep board before the fan heater, you can little bits of blueishness in the not yet fully dried coating, the fan heater has totally dried it. It also smells dry.

    [​IMG]
     
  15. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    I suppose may be true. What about all those solder joints? Were they coated? They did not look coated.

    In a little bit, I will put a wet salt water sponge on and see what happens. But first I will give it some time to cure.
     
  16. #12

    Expert

    Nov 30, 2010
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    :eek:

    Are you trying to make a product that is guaranteed to work in salt water???

    Please don't try following my example by running your hard drive in the laundry machines!
     
  17. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    I figure saltwater being a good conductor would show if Zep is a worthy coating. I was thinking make up about a 4% solution and fold a towel square and carefully soak a small area of the board, so it wont flow over the edges.

    :D

    So far it has been working good. Drive has warmed up and coating is not sticky or anything odd going on with it.
     
  18. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    Sorry, #12 -- I seem to have missed your post the first time 'round :oops:

    I apologize that my (admittedly cursory) post was found lacking in perspicuity...

    My point is merely that an 'RF' (i.e. Hertizan-EMR) absorbent lacquer is a 'bad deal' -- although such considerations may appear moot at the (fundamental) frequencies involved in many digital circuits, please recall that maintenance of rapid transition times will require many octaves of well-neigh flat (or predictable) response.

    Please note that it was not my intent to suggest that measurable RF/dielectric heating would present itself in actual application - but, rather, that such heating during intense 'RF' irradiation [of a test sample] would betray unacceptable dielectric properties...

    Best regards
    HP :)
     
    Last edited: Mar 24, 2015
  19. RichardO

    Well-Known Member

    May 4, 2013
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