Spray paint coming off parabolic solar cooker reflector Mylar coating

[Andrew Thornett]

Hi All,

Advice please!

As you can see from picture, the spray paint I used on the Mylar coating on the solar cooker parabolic reflector is coming off - what do I do?

Andy

[ja...@ganssle.com]

Andy,

 

When I paint metal I’ll sand it first, to give a slight roughness that act as “teeth” that the paint can adhere to. At 21 cm the roughness will not matter.

 

Jack

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[Andrew Thornett]

Thanks Jack. What is best thing to use to roughen a Mylar coating?

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From: sara...@googlegroups.com <sara...@googlegroups.com> on behalf of ja...@ganssle.com <ja...@ganssle.com>
Sent: Monday, March 31, 2025 10:09:53 AM
To: sara...@googlegroups.com <sara...@googlegroups.com>
Subject: RE: [SARA] Spray paint coming off parabolic solar cooker reflector Mylar coating

 

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[ja...@ganssle.com]

I’d recommend fine sandpaper. Not sure if sandpaper grits are universal across countries, but here in the USA I’d try 320 grit which is quite fine.

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[joe...@alpine-club.dk]

Hi Andrew

I´m also converting a solar coocker into hopefully a parabolic reflector. It has "rested" outside in the free and when looking into what I would do with the mirror surface,I found out it was quite easy to remove the mirror foil by lifting the foil with a knife and just tear the foil off by hand.

Have a try Andrew, it is easy but your might be different. Hope the best!

I will present my project later with photos etc.

Joergen

[Stephen Arbogast]

For  whatever it i s worth.....   I bought  the  Discovery Dish  from  Kraken RF  via Crowd Supply.  It is Aluminum   with   powder  coating.     Powder coating  is not  easily applied by  DIY...   but maybe   ......

[Marcus D. Leech]

On 31/03/2025 06:37, 'Andrew Thornett' via Society of Amateur Radio Astronomers wrote:

Thanks Jack. What is best thing to use to roughen a Mylar coating?

Yeah, sand it with fine sand-paper.  Then use "Krylon Fusion for plastics" at least as a primer coat.  IF you opt to peel the
  film off, the undercoat will probably be powder-coat, which takes ordinary lacquer and enamel paints reasonably well,
  rough it up a bit first with some fine sandpaper.

Mylar is basically PET, same stuff that pop bottles are made from.  Although, I'm nearly-certain that in the past, it was
  polyester based.

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[Andrew Thornett]

I've just tried peeling the Mylar off this morning and indeed it comes off quite easily so I will do that later in week!

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From: sara...@googlegroups.com <sara...@googlegroups.com> on behalf of Marcus D. Leech <patchv...@gmail.com>
Sent: Tuesday, April 1, 2025 6:14:56 AM
To: sara...@googlegroups.com <sara...@googlegroups.com>
Subject: Re: [SARA] Spray paint coming off parabolic solar cooker reflector Mylar coating

 

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[Adrian]

Andrew,

  You had mentioned that the solar cooker was experiencing corrosion/rusting being exposed outdoors.

 What portion of the dish are/where corroding was it the dish itself or the mounting hardware or everything?

Thanks.

[Marcus D. Leech]

On 01/04/2025 16:38, Adrian wrote:

Andrew,

  You had mentioned that the solar cooker was experiencing corrosion/rusting being exposed outdoors.

 What portion of the dish are/where corroding was it the dish itself or the mounting hardware or everything?

Thanks.

When I had something VERY similar 20 years ago (sweet googly moogly, has it been that long?), the rusting seemed to
  be concentrated on whether the mount hardware met the dish, and in a couple of spots on the surface where I had
  accidentally dented it slightly--popping off the powder coating--powder-coat isn't very flexible.

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[Andrew Thornett]

Pretty much wveryth8bg but spray aluminum and zinc paint is very effective at.stopping the corrosion

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From: sara...@googlegroups.com <sara...@googlegroups.com> on behalf of Marcus D. Leech <patchv...@gmail.com>

Sent: Tuesday, April 1, 2025 9:54:17 PM

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