Etch primer.

[waggy]

Good afternoon all,

I'm repainting an engine and have been advised by a fellow member to use Upol # 8 self etch primer on the steel smokebox.

Have any of you used this in such an application? If so are there any problems with flaking or roughening of the finish due to the heat?

Regards,

Waggy.

[jj]

Hi Waggy

I used the Upol on my Britannia smokebox, followed by Precision gloss black, and it is absolutely fine after five years and many steamings. The only caveat is that the Modelworks smokebox is very thick steel tube, and thinner metal might perhaps be more prone to hot spots.

Regards, John

[Doug]

May 29, 2015 14:57:52 GMT waggy said:

Good afternoon all,

I'm repainting an engine and have been advised by a fellow member to use Upol # 8 self etch primer on the steel smokebox.

Have any of you used this in such an application? If so are there any problems with flaking or roughening of the finish due to the heat?

Regards,

Waggy.

Hi Etch primer on steel is a bit of a myth. I will explane, the acid in etch primer is used to bond onto otherwise dificult materials that the paint cant normally adhere to these being , Brass,copper, aluminium and alloys of the them (also galv steel). steel is by nature quite rough textured and paint has very little trouble holding on to it if its clean. the very best way to "prep" steel is to media blast it there is no benefit what so ever to be gained by using an etch primer on it a normal primer will grab it just as well, the best thing to do is check the top coat paint (high temp paint) and see which primer it recomends. Dont waste your money on etch primer use Upol 1k primer its cheaper and the right stuff (just not sure about the temp range)
all the best Doug

[stan]

Hi Waggy
As Doug says you don't need to use etch on steel, I do because I had a gallon of Bodyline and activator when I finished at a spray shop. I worked on commercial vehicles and we used it mainly on truck chassis as it was near impossible to rub down for a key, only air tanks and fuel tanks were sanded and some of the chassis outside. If you do use it you must leave it to work 48 hours or more and I use cellulose paint for all my engines.
Stan

[andyhigham]

Getting paint to stick to steel is no problem, getting it off again is another matter now Nitromors has gone all limp wristed, politically correct and useless.
Automotive exhaust paint or barbeque paint is good for smoke boxes

[ukjimoo]

Hi all
I found Plasticote Woodstove Enamal from B+Q is excellent for smoke boxes. It easily withstands the heat, sticks like you wouldn't believe to bare clean steel, and looks great with a satin finish. Its a joy to use and i find it doesn't go thin on sharp edged parts as the spray is very fine.
It also sticks really well to clean copper so is good for spraying the backhead of boilers.
Jim

[denis M]

I have used SPAREX (or similar name) engine paint on smokeboxes before, you can get it in spray cans both gloss or matt from motorist shops. It says on the tin that it does not require an primer.
For removing paint I use Rustin's now that Nitromors has gone soft and does not work as good as it used too.


Denis

[chris vine]

Hi,

I have tried several of the high temp matt paints. some of them are very good while others are really poor and just rub off; they act a bit like soot!!

do some test pieces so you know what you have got before you do it for real on your engine which you have spent years making and maybe a year painting!!!

Chris.

[waggy]

Good morning all and thanks for all your replies.

I bought my paints and primer yesterday from a supplier in Collyhurst, Manchester. Had a chat with their very knowledgeable staff about primers and paint. The primer is a 2 pack etching product with a 200'C temperature limit, the topcoat synthetic a single pack with a 160'C limit. All a matter of putting the stuff on now! "Watch this space" as they say!

Waggy.

[GWR 101]

Hi Waggy, hope you don't mind me asking this on your thread but it is about smokebox painting. I have Chris's excellent book so am well aware of all the pitfalls but wondered how most people go about painting the area where the smokebox door seals. I know this sounds really basic and I am sure there is a straight forward approach but I cant see it. I assume its painted across the face with the door removed but how does this withstand the pressure of the door when closed. Or is it perhaps masked off so that the door seals on bare metal. Regards Paul

[chris vine]

Hi Paul,

Thanks for nice comment!! I have just painted the area which the door shuts onto. As long as the paint is properly attached (and suitably temperature rated) it will only get marked and shouldn't pull off.

It is a good idea to raise temperature in the boiler very slowly for the first few heats. Maybe not even to running temperature - the let the paint settle/harden even more. If you do that, you could just close the door and hardly tighten the handles at all. Then if it softens a bit on the first heating, it won't pick up.

Chris.

[GWR 101]

Chris many thanks for your advice which I have taken on board. I will also as mentioned earlier and in your book undertake some trial runs (not a word I should be using in connection with paint) to try out the etch primer and heat resistant paint (650 deg.) before working on the actual smokebox. And I thought building the thing was all there was to it. Regards Paul

[chris vine]

Hi again Paul,

I think Bongo to about 6 years to build and another (nearly) two years to paint. Most of that two years was mistakes and trial 'runs'...

On the smokebox I used etch primer and gloss black coach enamel, but drifted on to give it a lustre type of finish. It has stood up to a lot of use, but might never have got to the highest temperature that would be possible if the engine was slogging for 20 minutes or so. I just need a longer track...

Chris.

[GWR 101]

Chris many thanks once again all noted, and there was me hoping to get it running in the Autumn. The club elevated track is only a bit over 400 metres long so I am not expecting to run for extended periods, just to get it running will be my first target. Apologies to Waggy once again for hyjacking his thread. Regards Paul

[GWR 101]

Hi thought I would just update my efforts on smokebox painting, hope waggy doesn't mind.

After some trial runs I went for a Grey etch primer and a top coat of Black high temperature paint rated at 650 degrees.

And the result is :-

Honestly that smokebox is BLACK, it's actually the same paint that's visible inside the rear frame where at least it looks darker. I assume its the camera flash that has lightened it as it is a matt finish. I am fairly pleased with it and it appears to be well adhered.

I have had one issue brought to my attention since baking it in the oven, the oven light no longer works..... not sure if this was just coincidence or using it at the highest temp for 1 hour. Fortunately I had obtained permission from the catering manager to use the oven and although she had gone out when I did it there were some searching questions upon her return.

So tomorrow replacing the bulb will be "what I have done today".   Regards Paul 

[waggy]

Morning Paul,

Hi-jack as you wish, no problem.

Flash does give some surprising results, my Jubilee looks like it's painted Apple Green, not BR when flash is used!

My project going slowly but surely, while the loco's in bits I'm improving the cylinder lubrication system and adding a few more dashpots for the between frame "works".

Good luck,

Waggy.

[stan]

I don't know why people stay clear of cellulose paint easy to spray on with airbrush or aerosol tin, dries quick any runs can be flatted and repainted within a few hours, can be bought in Gloss/ Mat or Satin and withstands heat, all my models done in it.
Stan.