Making a Durable Aluminum Pattern For Casting Plaques

Discussion in 'Pattern making' started by Tobho Mott, Dec 6, 2017.

  1. Tobho Mott

    Tobho Mott Silver Banner Member

    Not a huge fan either... But you get used to it.

    Anyhow, just a quick pic of the finished plaque to show the silver paint touch-ups and glossy sealer coat:


    Red97 likes this.
  2. OCD

    OCD Silver Banner Member

    And why did you paint the embossments?

    Was there some filling pores involved and you wanted to hide the filer material?

    Yeah I'm going somewhere with this but await your answer first so I do stick my foot in my mouth.
  3. Oxide

    Oxide Lead

    Just a quick one, what grade sand paper did you use to get the shine on your numbers?
  4. Tobho Mott

    Tobho Mott Silver Banner Member

    The silver paint is just to cover up some black paint I was having trouble removing from some tiny pits along the very edges of some of the raised sections. Here's a close up of the left side of the 6 where the worst of it was.


    I think it looks fine now when you're not looking at it right up close like that, now that the black paint isn't showing in there anymore to draw the eye and break up the smooth edge. No fillers were used.

    But please, do tell - I'm definitely here to learn and very interested to hear about it if you (OCD) or anyone else would have approached this differently.

    Oxide - I used some 100 grit then when I was taking the black paint off the numbers and border I think I was using some small scraps of 220, I didn't see any reason to go beyond that. A couple coats of spray on glossy sealer helped shine it up a bit more too.

    Last edited: Feb 10, 2018
  5. OCD

    OCD Silver Banner Member

    First off, any time you plan on painting aluminummmmmm, it needs to have a base coat of zinc chromate or phosphate applied.
    If you go and look up the application parameters for the phosphate it's going to tell ya it's only for steel. Wrong, it works on aluminum as well.

    Once it's applied and the correct amount of flash time has elapsed you can apply your top coat.

    In reference to the embossed areas.
    If finances are an issue the caster can take a bar of soap and coat the areas they wish not to end up painted one finished.
    The soap will not only provide a barrier but fill all those pits in and keep the paint out.
    After it's painted and sanded you can easily scrub the remaining soup out of the pits.

    In reality, you could also apply some crystal clear resin to the embossments as well prior to painting since the embossments are gonna end up getting sanded anyways.
    You would have to apply multiple coats though to build up the bottom of the pits to become level with the original highest surface point.

    The is latex rubber masking on the market that can be applied to areas one wants to protect from becoming painted as well.

    Years ago I ran a paint department for a LARGE sign manufacturing corporation and used a product called Spraylat.
    It's a latex base masking used on all kinds of signage and illuminated acrylic faces and the like.

    There's other product out there called Sign Stripe which does the same thing.

    Here's one ink just to show you what it is.

    Shop around for pricing.

    You brush or spray it on, let it cure, (usually over night or 8 hours depending on mil thickness) cut around the outlines or area to be kept masked off with an exacta knife, peel away excessive masking or areas to be painted.
    Once product is painted, peel of remaining masking.

    Or you could stop pouring aluminum Kelly sent you. ;) :D No more holes.

    Just ribbing ya Kelly.

    Seriously, go by a darn replacement belt for your sander.

    A regular ole electric orbital hand sander would resurface those embossments down with the correct sandpaper.
    Would take awhile but it can be done.

    Went prepping aluminum surfaces after a casting, 150, 220, 320, 400, 600 and polish out with some mag polishing cream.

    There's all kinds of clear metal protector sealants out there to seal your metal projects with.
    Just make sure the top sealant coat has the same solvent content as the base coat. (E.g., water based, solvent based, etc.)

    If you spray a solvent based sealer over a latex based paint it'll gator it and cause crinkles/wrinkles.
    You can spray or apply oil over water but can't apply water over oil.

    There so many different ways and products you can utilize to apply to you projects to result in a quality finish.
    Tobho Mott and Oxide like this.
  6. Tobho Mott

    Tobho Mott Silver Banner Member

    Thanks OCD, that is a lot of info and mostly all new to me. Hopefully the couple tiny spots of silver craft acrylic paint under the clear gloss polyurethane won't cause too much trouble...


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