Chrome blueing -- how to simulate?

[chepp]

What do you suggest for simulating the bluish/brownish discoloration of chrome 1/25 scale exhaust headers? I'm building a model of a '50s hot rod with exposed headers that gets driven often so I want some coloring but not an excessive amount. I'm having no luck finding photos other than of motorcycles since most folks polish things up before shooting pix. Can you post a link to one or more tutorials?

Online searching for this is nearly impossible because phrases like "chrome blueing" turn up all sorts of unrelated things.

All I could find is

Scroll down to see a couple of photos...but they don't look convincing.

[Bainford]

I have used Tamiya clear blue, sprayed lightly with an airbrush to good effect. I have also seen work by others using blue and purple sharpie type markers that looked very good, too. A little experimentation with scrap parts is recommended.

[Richard Bartrop]

Basically, airbrush clear blue onto your pipes, with a little clear orange around the edges. Open up the paint flow just the tiniest amount, since you're going to be doing some very fine work.

Also, try "Chrome discoloration" as a search term.

Edited January 5, 2021 by Richard Bartrop

[peteski]

I also airbrush light feathered coats of Tamiya clear paints. Blue and even some red as a second coat in certain areas.  Blue and red results in puple color. I guess clear orange woudl add even more realism.

[Bills72sj]

You could also experiment with food coloring mixed into some Future floor wax. Keep the colors separate until dry. Mix it dark in the dixie cup and apply with a brush. Do not stroke it once it starts to solidify. Clean up with water. If you want to do it over, gently remove with household ammonia.

[935k3]

Try Tamiya weathering set 'D', it has clear burnt red and blue. It comes off with ammonia if you want redo it. It's applied like makeup.

[misterNNL]

23 minutes ago, 935k3 said:

Try Tamiya weathering set 'D', it has clear burnt red and blue. It comes off with ammonia if you want redo it. It's applied like makeup.

Hobby Lobby has the Tamiya weathering sets in their model car paints section and with their weekly 40% coupon available on line they're not too costly.

[El Roberto]

 

[Misha]

I’ve also used the Tamiya weathering kits D & C for heat and highlighting weathering effects. It allows for a subtle shading without the effort of running an airbrush. Although for larger scales than 1/25 I would choose the Tamiya transparent shades thru an airbrush.

Cheers Misha

[89AKurt]

2 hours ago, El Roberto said:

 

I'd like to see photos of the real deal that looks like that! ?

 

[peteski]

1 hour ago, 89AKurt said:

I'd like to see photos of the real deal that looks like that! ?

 

A little artistic license is allowed.  Just take a look at all those figure painter models who seem to exaggerate shadows and highlights on their figures.

[peteski]

I have only done the heat-bluing process on motorcycle models. Here is one of them (1:12 scale HD Springer).  I think that even on that one it is slightly overdone (by me).

 

[vintagerpm]

Alclad also makes various shades of paint for heat discoloration.

Mike

 

[Casey]

https://www.tamiya.com/english/howto/bike1/tip1.htm

[chepp]

Thanks for the help! I'll try airbrushing thinned Tamiya clear colors with a VF needle/tip first. Here are pix of some actual pipes.

I'll probably try for a toned-down copy of the coloring in photo C with a little blue as in photo H.

This link also has some techniques to consider: https://www.reddit.com/r/ModelCars/comments/8d1ty9/id_like_to_simulate_this_bluing_on_crome_exhaust/ .

Edited January 7, 2021 by chepp
Better explanation.

[Deuces ll]

Picture "H" looks like it was running a little lean..... That will stain chrome pipes all the time.....??

[Straightliner59]

I did this with one of the Tamiya weathering kits.

[Erik Smith]

On 1/5/2021 at 8:08 PM, El Roberto said:

 

Way over done, but basic process is there. Look at actual exhaust like in your photos above. 
I use the Alclad version - they have a whole range of colors for heat coloration.  It takes such a small amount I think I’ve had my alclad paints for ten years and there still 3/4 full. 

[chepp]

Here are some tests of various transparent colors and solid powders.

1    Clear yellow, 2 coats
2    Clear yellow, 2 coats + clear orange, 3 coats + clear blue, 2 coats + clear brown
3    Clear yellow, 2 coats + clear blue, 2 coats + clear brown
4    Clear orange, 3 coats + clear blue 2 coats
5    Clear orange, 3 coats + clear brown
6    Clear blue, 2 coats
7    Weathering powders: metallic copper + salmon; paint: clear blue
8    Weathering powder: blue; paint: clear brown
9    Clear brown

 

Paints:
Clear yellow: Tamiya gloss clear X-22 + clear yellow X-24 + X-20A thinner
Clear orange: Tamiya gloss clear X-22 + clear yellow X-24 + clear red X-27 + X-20A thinner
Clear blue: Tamiya clear blue X-23 + X-20A thinner
Clear brown: clear yellow mix above + clear red X-27 + clear blue X-23 + clear smoke X-19

Powders:
Metallic copper: Tamiya Weathering Master, set F
Salmon: : Tamiya Weathering Master, set G
Blue: Bragdon Enterprises The Blues

Here are two colors on an actual part. It looks better in real life. The brown is heaviest nearest the head flanges then fades to nothing halfway down to the tailpipe flange. The blue is heaviest nearest the head flanges and fades to nothing where the three pipes become one. All of the examples were airbrushed with a Badger Krome Renegade with the VL needle/tip at 12-15 psi.

 

The Tamiya powders are intriguing. Unfortunately, the most desirable set D was out of stock but those transparent blue and red colors should be good to try. I didn't have much luck in using any of the powders. I think that they need a matte or flat surface for best results.

[Straightliner59]

6 hours ago, chepp said:

I didn't have much luck in using any of the powders. I think that they need a matte or flat surface for best results.

I suspect that the powders are nothing more than ground pastel chalks. It does work great, and look beautiful applied to flat or semi-gloss paint, but, it definitely needs some "teeth" to stick  to. Then, it needs to be set with a clear coat. Many people use hair spray, to set it. This chassis is pastels over semi-matte black, dry-brushed with a mixture of oils and enamels. Finally, working in sections, I applied a mixture of ground pastels. and set it with Dullcote. I need to coat the chain with something oily-looking.

[chepp]

11 hours ago, Straightliner59 said:

I suspect that the powders are nothing more than ground pastel chalks...

 

They also have an adhesive in them that help them stick. I've used them a little bit on HO model railroad items but always on flat paint. Your work looks excellent. For the oily chain you might want to try brushing on Tamiya Clear Smoke. It's glossy and semi-transparent so the silver color will show through. I see that you are in Arvada. So is Bob Black, the moderator for this 1/25 model car site: Traditional Rods and Kustoms in Miniature. His monicker there is RodBurNer.

 

...and your Gate City Spl. build and exhaust pipe coloring (see Thursday, Jan. 7 post above) looks fantastic.

Edited January 9, 2021 by chepp
Added comment about Gate City Spl.

[Big John]

On 1/6/2021 at 4:17 PM, chepp said:

Thanks for the help! I'll try airbrushing thinned Tamiya clear colors with a VF needle/tip first. Here are pix of some actual pipes.

I'll probably try for a toned-down copy of the coloring in photo C with a little blue as in photo H.

This link also has some techniques to consider: https://www.reddit.com/r/ModelCars/comments/8d1ty9/id_like_to_simulate_this_bluing_on_crome_exhaust/ .

Generally as with using color as a guide in heat treating metals, as the temperature rises the colors start running from pale yellow through straw, orange, red, purple to dark blue at the hottest point before the metal starts to glow. G&H show where the hottest point is right at the entrance to the pipes and the color fades as the gasses cool somwhat. Also any bend or kink in the pipe will be a location where the heat will build as the gasses hit the outside wall of the tube as in A& E.  In F there are restrictions where the flex pipes connect to the headers and this captures more heat but not enough to blue.

Edited January 20, 2021 by Big John

[chepp]

On 1/5/2021 at 6:49 PM, 935k3 said:

Try Tamiya weathering set 'D', it has clear burnt red and blue. It comes off with ammonia if you want redo it. It's applied like makeup.

 

The "D" set was finally restocked -- mine came from Burbank's House of Hobbies. Wowee! It's a transparent blue, red-bronze and gray set.

I recommend it. It even sticks well to "chrome." Thanks, 935K3.

[Mile High Scale Modeler]

I have seen modelers who dechrome, paint the part dark blue, then paint over with Alclad Chrome. Using blue as a base instead of black give that blue hue to the chrome which will help and then continue with your method of heat staining. 

[chepp]

9 minutes ago, Mile High Scale Modeler said:

I have seen modelers who dechrome, paint the part dark blue, then paint over with Alclad Chrome. Using blue as a base instead of black give that blue hue to the chrome which will help and then continue with your method of heat staining. 

Thanks! That sounds like a good idea.