Treating flaking steel garage door

Discussion in 'Painters' Talk' started by Bodgitandlegit, May 24, 2010.

  1. Any advice please as to the best course of action for a zinc dipped, steel garage door. The original paint layer complete with gloss, undercoat and primer (if it had one) is peeling in places. Mostly in the hard to reach areas in the narrow grooves. The layers of paint flaking off are so thick that feathering the edges is not an option. Would it be best to strip and start again? Can anybody recommend a stripper that they've had good results with? Then what about the primer, will I need a special primer for zinc, or will ordinary metal primer do? The planned finish will be one primer, one undercoat and one or two gloss as required. Thanks, Les
     
  2. Goodwill

    Goodwill Member

    Hi Les,

    Sounds like this door was not weathered or alternatively, pre-treated.

    I would suggest that you strip it right back to the zinc coating. You can choose which method to use, heat gun, gas torch or spirit paint remover. If you choose to use heat then play the flame or heat source over a small area at a time then remove the paint with a 2" or 3" stripping knife. Do not heat-up the metal too high, keep the heat moving.

    I would recommend that you apply a spirit paint remover in the quirks, such as Nitromors, and remove the paint using a coarse/medium grade of wire wool. Wash/wipe the door down with white spirit. When dry apply a mordant solution (see pack for instructions). Prime with a product such as Dulux Trade Metalshield Zinc Phosphate Primer (note: it is a fairly high build paint). If you decide to stay with Dulux Trade products then you could apply two coats of Dulux Trade Metalshield Gloss. Dulux also supply a mordant solution.
     
  3. Thanks for your help, Goodwill. I've tried using heat to strip paint from metal before without a lot of success. If you reckon it works, I'll give it another go. Thanks for the mordant tip. I've never heard of it before. I always thought it refered to the fixing of a dye in cloth/wool. Cheers, Les
     
  4. jcts

    jcts Active Member

    I agree with goodwills paint recommendation. However I don't know why you have advised to T wash it. A mordant solution is to prepare new galvanized metal for painting
     
  5. Goodwill

    Goodwill Member

    Hi Jcts,

    White spirit to remove any residues left behind by the paint remover, especially wax, or use water if a water washable remover has been used. This is to ensure that nothing is left behind to ****** the drying of the new paint system.

    The mordant (meaning to give bite - for instance; gold size is a mordant) solution should not be relied upon to remove the wax residues of the paint remover.


    Hi Les,

    I prefer using an adjustable propane gas torch when burning paint off metal. Remember that heat rises so start at the bottom and keep heating the paint by constantly playing the flame over the surface, stripping the paint immediately when the surface begins to flare or shows immediate signs of destruction.

    If the paint is not removed in one go then re-heat the same place immediately and strip again, repeat until all the paint is removed. Finish off by lightly re-heating and lightly rubbing down with say 220 aluminimum oxide abrasive.

    If you find it difficult to develop a satisfactory technique then use a paint remover throughout.
     
  6. jcts

    jcts Active Member

    When dry apply a mordant solution (see pack for instructions)

    I ask again, why have you advised this? A mordant solution is to prepare new galvanized metal for painting
     
  7. Goodwill

    Goodwill Member

    The smooth greasy surface of new galvanized steel provides little or no key for paint hence the application of the mordant solution to give 'bite'. It would appear that this door was painted when it was new without being given the treatment of a mordant solution or being allowed to weather.

    Paint, with failing adhesion because of the lack of preparation, has covered this galvanized surface from outset and so it can, therefore, be assumed that this galvanized steel in a condition very similar to that on the day when it was first painted. If it is not re-prepared properly then it is likely to fail again.
     
  8. potty painter

    potty painter New Member

    I think you will find that Goodwill could not be sure if the door was weathered or indeed if a mordant solution had been applied.

    Hence is advice.

    Potty.
     
  9. potty painter

    potty painter New Member

    Goodwill.

    You beat me to it.

    Potty.
     
  10. Goodwill

    Goodwill Member

    Cheers Potty.

    I couldn't quite get to grips with why these factors simply weren't occurring to Jcts. Must have been at the end of a long day. ;)

    Regards

    Goodwill
     
  11. potty painter

    potty painter New Member

    Goodwill.

    Thanks for the reply.

    Have a good bank holiday weekend

    Potty.
     
  12. jcts

    jcts Active Member

    Goodwill, ******** to you because i'm too old and tired to explain myself
     

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