Stripping paint off a Dynaco ST-70 nichel

I have a Dynaco ST-70 which has been painted with white primer.

I can actually strip some of the paint away by just scratching it, but I would prefer to not scratch the nickel of the amp.

Do you have any trick or product I could use?

Also the transformers are painted. Any trick I could use on both too?

Thanks
 

rayma

Member
2011-04-29 8:37 pm
I have a Dynaco ST-70 which has been painted with white primer.
Also the transformers are painted. Any trick I could use on both too?

Try paint thinner from the hardware store. First disassemble everything, and also remove
the metal end bells from the transformers. This will likely also remove the silk screening
from the chassis, though.
 
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What's the problem with white primer?

It's not the definite paint but a base, now you lightly sand it with grit #600, and apply finishing paint, any you like.

If you peel primer (or paint) down to bare metal, you'll have to treat it, apply some primer and final coat anyway or fully disassemble the unit, send parts to fully clean (sandblasting recommended) and galvanize with the metal you like, usually zinc but maybe nickel or chrome, any of these preferrably applied on an intermediate layer of copper.

What you can not do is to leave any iron surface exposed to air humidity and oxygen.
 
I have tried with acetone so far. It doesn't seem to thin the pain enough. I found out that scratching it with corners of wood sticks makes the paint chip away. So far I've removed 50% of the paint off the nickel of the amp, still waiting to complete the work.

On the transformers and the multi can filter instead seems that the paint sticked better. I don't think I'll be able to remove it by just scratching it...

The nickel itself, once exposes, is pitted. So I tried polishing it with with this Eastwood Buffing Kit (Eastwood Buffing Kit - Paint Buffing Kits - Buffing and Polishing Kit), using the white compound, which on the instructions seem the first compound to try on nickel.

It doesn't really remove much though...but I have to try more extensively once I chip all the white paint away off the case.
 
The nickel itself, once exposes, is pitted.
And that's why the former owner applied primer on it ;)

You have 2 options:

1) if you want to go the full Monty: disassemble the amplifier until you have only the nickel plated chassis (really the nickel plated part), and send it to a metal plater /finisher.

You sand it smooth, down to metal, because plating not only does not hide imperfections but shows them better, because of the metal shine, and it's as new.
I strongly suggest, if they don't say it themselves, that you ask them dual plate: first a layer of copper , then nickel.
Don't worry, they'll know what you are talking about, they see it every day.

Nickel can be applied straight to iron but is porous; if ambient is too humid you end up like it is today ; after many years but it happens; while copper base seals the pores.

b) accept paint as a reality of life :(
Sand it smooth again , wipe surface with phosphatizer to kill tiny rust pinpricks, wash, apply primer , IF needed lightly sand smooth and apply finish paint.

If too pitted apply some textured finish paint similar to Hammerite, there's many cool ones to choose from.
[IMGDEAD]http://www.kilz.com/MCContent/MC_Article/Hammerite_Rust_Cap/HRC_Article_Images/HRC_ArticleImg_HammeredColors_427x411.JPG[/IMGDEAD]
 
Thanks guys!

I think I will try with option 2 of JMFahey.

I'm trying to fix it on a budget, in the end it is a quite a beaten up unit, so I'm not too precious about bringing it back to perfection. But I would like to "play" with it, clean it, make it nicer, and meanwhile learn new things like how to polish nickel and apply some protection :)
 
rayma's suggestion is a good one, if you'd planned on a complete tear-down and rebuild

while yer at it why not replace some of the flaky original mechanical parts, but by the time it's finished you're looking at dozens of hours and several hundred dollars - these things always take more time and $ than you'd hope :eek:

he knows this, how?
 

rayma

Member
2011-04-29 8:37 pm
while yer at it why not replace some of the flaky original mechanical parts,
but by the time it's finished you're looking at dozens of hours and several hundred dollars ?

Tell me about it. I could build several new Dyna amps in the same time it takes to restore one old one.
And you usually need to replace all the parts (except the iron) anyway.
 
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