Petromax HK250 restoration

I got an old 250 from the web. I know my way with Petromax but this problem had not occurred to me: I removed the pump piston and lots of rust fall out. The pump cylinder (98 of the plan) has rust! I used a tooth brush to try to clean it but still I see rust inside. The lantern is definitely an "Original Petromax Made in Germany" (nickel plated).

Is there a way to clean it and restore it? Any chemicals that could be used? Something else? How can there be rust there? Or it is not rust? I looks like rust though.

 

I would not know of pump cylinders made of steel which could corrode. These were made of brass.
But as you do have rust in there: soak in in WD40 or something similar for a few days and then try to wash off the rust particles.
What does the tank look like inside?

Erik

 

OK, I will try that with WD40 and see how it goes. The tank inside looks clean. I also washed it with water and water came out clean even the first time.

 

Antonis, l have heard of people using a "break cylinder hone" to clean out rust in steel pump tubes.

 

What is a "brake cylinder hone"? Never heard this. How bout using fine sand paper after the soaking with WD40 say for 2 days?

 

You mean (I guess) something like this: https://www.toolsonline.gr/en/speci...2mm-89mm-11-4-31-2-toolsonline-shop-50:v.html
But what does the size means? This says 32ΜΜ-89ΜΜ(11/4"-31/2"). But there are other sizes too. Maybe sand paper is simpler...

 

Cut a slot across the end of a short length of wooden dowel. Insert a small length of fine emery cloth into the slot and wrap it around the dowel a few times. Put the dowel into a battery drill and clean the inside of the pump tube.

 

Nice trick. Will try this first after soaking in WD40.

 

The trick with the drill worked fine. Brass is now visible inside the cylinder and feels very smooth. At some points though there are some red spots. So this is probably exposed copper? However, the base of the cylinder around the valve looks also "rusty" and this can not be cleaned most probably... Or there is another trick?
By the way what do you do with the rust on the inner casing (No 117) (the part that holds the mixing shaft)? This is probably pointless to try to remove rust....
And what about the bail? Can this be removed to clean it easily? The nuts holding it stop at some point when you try to unscrew them.

 

I was wrong about rust in the bottom of the pump cylinder. It was old oil deposits from the lather of the pump. It looked like rust, it wasn't. Now I will move to change wear parts and polish it.

 

Easiest way to determine rust is the use of a magnet.

 

Correct, thanks. Part 122 the centering bottom gets magnetized and it is very rusty as you can see below.
I tried using sand paper (as you can see at the center of it) but is hopeless. Too much work. Can I use a chemical like desoxidante? It is a rust remover. I just wonder if I risk anything. Since it is magnetized it is not brass. What is this made of? Under the rust it looks silvery.

 

Citric acid or vinegar will get you going??


yes, rust removers are available but can be costly and don’t really justify the expense on this occasion?
if it was enamelled or similar then maybe?

electrolysis would also work?

 

Great. So I will proceed with some acid. Question: If acid (like vinegar) is applied to the tank which is nickel plated is this dangerous for the tank's integrity? The tank is very dull. If it is safe to use vinegar it will facilitate the removal of debris/salts on the surface. But I wonder if it is safe for nickel plated brass surfaces such as the tank.

 

Antonis, for brass, reduce the strength of the vinegar by mixing equal amounts of vinegar and water. Don't leave it in the solution very long, about 3 to 4 minutes then take it out and wipe it over. If needed repeat. If you leave it in too long the zinc will be etched from the unplated brass surface and it will go copper in colour.

 

OK thanks. I will see what I will do. Maybe better to avoid acids on the tank and insist on petromax polishing paste...

 

Just out of curiosity, even if the brass surface is nickel plated as this lantern is, will again vinegar etch the zinc of the brass below nickel?

 

Antonis, I don't know if the plating will protect the brass.
I use citric acid regularly and have used vinegar on brass. Either way the point is to not leave it in the sollution too long.

 

OK, let me ask something else. The plate I picture above (#122) needed several attempts to remove rust. It was too rusty. Now this is magnetized so it is not brass. It looks like something like steel (maybe stainless?). Now that I removed the rust, is there a way to help it preserve its current state, mainly when it is in storage? I still have to replace all kind of gaskets (I have ordered them and wait to receive them), but after I test it and is in working state, it will be put in storage/display. How can I avoid it getting rusty again? Because this was the most damaged part so far. The rest of the lantern is nickel plated brass, but not this one.

Another metallurgical question: What will happen if a piece like this, if it gets rusty again, be painted with tannic acid? This converts the rust to metal again and bonds to the surface. Of course it will become black, but does this withstand the heat of the lantern? I guess this piece does not get too much hot as air passes through its holes to provide oxygen to the flame. Hot, but not extremely hot.

 

The cage base plate you showed is almost certainly mild steel not stainless.. stainless can rust, despite its name but it needs to come in contact with rusty steel first which contaminates it.

there are high temperature silver coloured spray paints which have been used successfully by members?

also members have done their own nickel plating for pieces like this using the old school battery chargers and making their own electrolyte

you can use a rust converter but the object needs to be painted or protected as soon as possible as exposure to air will start the rust again

there are cheaper rust converters and you pay for what you get, in my opinion, so i would pay more for a better quality type?

 

Thanks. I will examine my options...

 

This thread called ‘Nickel plating at home’ is encouraging ?

i found it by using the search bar

they recommend looking on youtube as well

 

A good way to remove rust will be phosphoric acid. It leaves also a protective layer of dark coloured iron phosphate ready for painting, but impossible to solder (just use the Google KI search with the prompt "phosphoric acid as rust protection".

 

I tried to remove rust with citric. I applied many times until it was possible to remove the last rust with sand paper. After sanding (by hand) the above part turned out like this:





So rust is gone. But the metal has black stains. I though this would be burnt oils, so I applied "WD40-Multi purpose degreaser", but did not do anything. It stayed the same. So either the black stains are not burnt oil or the Multi purpose degreaser I used is not capable of cleaning it. I guess I can not attempt a nickel plating procedure if the metal is not completely clean. Or can I? If I can plate it while being in such a state, I will order some nickel to try and learn the home electrolysis procedure.

 

I use automotive paint for these situations: a ceramic paint used for brake callipers or engines, either aluminium or silver colour.

I use a paint that does not require high temperature curing, so the calliper paint I use does not require heating in an oven.


Best regards

Tony

 

Can you give me an example of a product so I can find a similar in the local market?

 

@Antonis Tsolomitis

In Australia—>




There’s a brake calliper range also.


Cheers

Tony

 

Thanks. I looked everywhere. These products are very rare in Europe, and if you find them in some country (eg Dupli-Color Silver Brake Caliper Spray 150ml - ColorShop.cz) they can not be shipped. The only available option among all these (VHT, Por-15, Dupli-color etc) is a VHT clear caliber spray "VHT Brake caliper enamel gloss clear". All other colors are just unavailable. Maybe this relates to the trade war between US and EU. I do not know... it is very strange. So since VHT transparent is my only option, I will go for that. Unless there is a way for nickel plating...

 

@Antonis Tsolomitis

Try asking a motorcycle repair and accessory shops. Motorcycle fans often have exotic paints for engine parts and tanks. You don’t need very high temperature paints as this plate does not get too hot, but you do need a paint that is resistant to fuels.


Tony

 

Good idea. I will ask them.