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Painting a metal dome?

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#1 EdM2

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Posted 23 June 2021 - 09:46 PM

Does anyone have any recommendations for painting a metal observatory dome, such as:

 

1)  What kind of paint is best to give a long lasting finish (brand name)?
2)  Should the paint be flat, satin, etc.?  My HOA would not let me use glossy.
3)  Should the dome be primed first?  If so, what kind of primer would be best to use (brand name)?
4)  What kind of spray gun works best to paint the dome smoothly (brand name)?
5)  Does he have any other recommendations for my local painter?

 

Any input is appreciated.  Thanks.

 



#2 Dynan

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Posted 23 June 2021 - 09:54 PM

1) Rust-o-leum White

2) Satin might be best. Flat might promote mold in more shaded spots.

3) Yes. Rust-o-leum

4) Binks

5) Do it for free and come look through my telescope for free. lol.gif

 

EDIT: Forgot to mention the obvious...Oil Base for everything


Edited by Dynan, 23 June 2021 - 10:01 PM.

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#3 PETER DREW

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Posted 24 June 2021 - 04:10 AM

What type of metal?  If aluminium I would leave it unpainted, my 30ft aluminium dome is still good after 21 years.


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#4 mark77

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Posted 24 June 2021 - 08:12 AM

For some metals, an acid etch first is very important.  I painted an oil tank and did not do that.  The paint came off in sheets as big as 1 foot square.

 

Re-did with an acid etch and it worked fine.  Acid etch is available at your local hardware store.


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#5 EdM2

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Posted 24 June 2021 - 08:27 AM

What type of metal?  If aluminium I would leave it unpainted, my 30ft aluminium dome is still good after 21 years.

I believe it is steel, painted silver and coated with a protective coating to prevent corrosion.  The reason I am repainting is that my HOA says that the dome is too "shiny" as is and they want it painted a color that matches in better with the community.

 

A source, knowledgeable with the subject tells me that Elastomeric paint is what most observatories use.



#6 EdM2

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Posted 24 June 2021 - 08:32 AM

For some metals, an acid etch first is very important.  I painted an oil tank and did not do that.  The paint came off in sheets as big as 1 foot square.

 

Re-did with an acid etch and it worked fine.  Acid etch is available at your local hardware store.

Great point.  My case might be different however since the dome was already painted and coated at the factory.  I assume they etched the metal surface before the original painting.  In my situation it would essentially be a case of paint over paint.



#7 Dynan

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Posted 24 June 2021 - 08:58 AM

Have your painter look into 'bead blasting' the dome to strip it down. 

 

HOA's..the BANE of Mankind! noway.gif



#8 cmaier

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Posted 24 June 2021 - 10:51 AM

Following, This was the reason I went with the 10' home dome vs the ash dome.. Had to be colored the same as the house stucco, which they did. Wasn't sure how to paint the ash dome to make it last. 



#9 John Fitzgerald

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Posted 24 June 2021 - 10:56 AM

It's a brand new dome.  I would tell the HOA that it will naturally turn gray in several months.  Removing the coating to paint it would probably ruin your new Ashdome.  No way I would strip it and paint it.  Tell them to pound sand.

 

Edit: If it's paint over paint, and the paint is compatible, it should work. Any color other than a very light one will cause it to be intolerably hot.

 

https://www.hopb.co/...-can-go-too-far


Edited by John Fitzgerald, 24 June 2021 - 11:21 AM.


#10 DSOGabe

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Posted 24 June 2021 - 11:20 AM

 The reason I am repainting is that my HOA says that the dome is too "shiny" as is and they want it painted a color that matches in better with the community.

 

 

ohmy.gif  HOAs....Geez


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#11 astrokeith

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Posted 24 June 2021 - 11:32 AM

Professional domes would use an IR reflective paint.

Is white going to be OK, or is that too bright for the HOA!!

 

My dome is dark green (technically it is British Racing Green!), to fit in with my wooded garden. It has a clear overcoat, that is IR reflective. 15 years old now and I've lost the paperwork I'm afraid.



#12 vrotondi

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Posted 24 June 2021 - 11:39 AM

You should ask Ash dome for advice on this...


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#13 Christopher Erickson

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Posted 24 June 2021 - 07:00 PM

Be aware of priming/acid-washing, metal thermal expansion, UV reflectivity, etc. 

 

I prefer paints with maximum reflectivity of solar energy, are elastic enough to expand and contract with the dome, and are capable of a REALLY good bond to the dome surface.



#14 John Fitzgerald

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Posted 24 June 2021 - 07:11 PM

You should ask Ash dome for advice on this...

Yes!



#15 EdM2

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Posted 06 July 2021 - 02:06 PM

For some metals, an acid etch first is very important.  I painted an oil tank and did not do that.  The paint came off in sheets as big as 1 foot square.

 

Re-did with an acid etch and it worked fine.  Acid etch is available at your local hardware store.

Mark,

 

My painter wants to use M1 Deglosser shown below:

 

https://www.sherwin-...repaint-cleaner

 

Is that the same as an acid etch?



#16 Stevegeo

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Posted 06 July 2021 - 05:45 PM

I would use a ureathane auto paint mix , over a ureathane  primer .  If metal is bare, a go over with a fine paper to remove any nasties , a rinse off then dry.. PREP IS EVERYTHING!!  A final sand then tacky ragged down. 

A good  warm day with low humidity , a good paint gun ,  steady hand , zoot suit , respirator  , and as I

KEEP SAYING PREP IS EVERYTHING.. 

this is high end finish, done right your HOA nazis  will approve .

Three coats will give an auto finish that will last longer then YOU . 

 

Stevegeo 



#17 John Fitzgerald

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Posted 07 July 2021 - 02:09 PM

Ed, what color are they forcing you to paint it?  Hopefully not a dark color that will overheat the inside.



#18 speedster

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Posted 09 July 2021 - 10:44 PM

The deglosser is not a finish.  It's an intermediate coating to improve adhesion of the next coat. 

 

Elastomeric is not needed.  It's about 10x thicker than what you want but can still be sprayed but usually required back-rolling which leaves you with an orange peel texture.  We use a lot of elastomeric coatings but never as an exposed to view finish.

 

You might contact Eastwood.  They have the expertise and products to guide you.  https://www.eastwood.com/


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#19 EdM2

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Posted 13 July 2021 - 12:05 AM

Ed, what color are they forcing you to paint it?  Hopefully not a dark color that will overheat the inside.

They allowed me to paint the dome a rather light beige.  It actually looks pretty good.  It also blends in well with the desert environment.



#20 EdM2

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Posted 13 July 2021 - 12:07 AM

I would use a ureathane auto paint mix , over a ureathane  primer .  If metal is bare, a go over with a fine paper to remove any nasties , a rinse off then dry.. PREP IS EVERYTHING!!  A final sand then tacky ragged down. 

A good  warm day with low humidity , a good paint gun ,  steady hand , zoot suit , respirator  , and as I

KEEP SAYING PREP IS EVERYTHING.. 

this is high end finish, done right your HOA nazis  will approve .

Three coats will give an auto finish that will last longer then YOU . 

 

Stevegeo

I believe my painter did something like this.  


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#21 eastwd

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Posted 13 July 2021 - 12:19 AM

Hope you’ll post photos of the dome with the new paint job when you have a chance, Ed.



#22 John Fitzgerald

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Posted 13 July 2021 - 08:03 AM

They allowed me to paint the dome a rather light beige.  It actually looks pretty good.  It also blends in well with the desert environment.

Hopefully, it won't cause the dome to overheat.  The original silver is on the AshDome for a reason.



#23 SkipW

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Posted 13 July 2021 - 09:22 AM

The original silver is on the AshDome for a reason.

I always thought the reason was because that's the color of galvanized steel.



#24 John Fitzgerald

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Posted 13 July 2021 - 09:34 AM

I always thought the reason was because that's the color of galvanized steel.

I think it's painted with Aluminum paint over the steel.  The one I have been in seemed to be.  Galvanized steel turns grayish fairly rapidly.



#25 SkipW

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Posted 13 July 2021 - 11:52 AM

I think it's painted with Aluminum paint over the steel.  The one I have been in seemed to be.  Galvanized steel turns grayish fairly rapidly.

The older ones (ca. 50 years) were unpainted except in places where the steel was exposed during manufacture. Those limited areas were painted with metallic paint to match the unpainted metal reasonably well.

 

I don't have direct experience with newer domes, but the last page of recent assembly instructions say:

 

PAINTING

 

All ASH-DOMES are fabricated of galvanized and Galvalume steel. These materials do not require painting. Should it be desired to paint your Ash-Dome it is recommended you contact a local paint supplier and seek a paint used on commercial metal buildings.

 




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