I’m sure it has been answered a hundred times b-4 but how long should I leave photo etch parts in vinegar to prep it for paint?
Hello!
I dunno - I don’t do it at all. But I also don’t think anything but the first minutes do any difference here. As I understand it the idea is to passivate the brass, so that the primer has a better grip. I wonder what other have to say here. Good luck with your modelling projects and have a nice day
Paweł
Never heard of that one. Does it really make any differance.
I’ve never put PE parts in anything to prep them for paint. I cut them out and glue them in, and paint them. Haven’t had a problem yet.
I have been dealing with pe for many years and I only use a good solvent type primer such as decanted Krylon or Rustolium as paint prep. Tamiya primer is excellent.
I just hit em with either Mr Surfacer or Tamiya,never no problems.
I was thinking this post needed to be in foodnetwork.com/salad forums? [:D]
Huh? The most ridiculous thing I’ve ever heard. A simple coat of primer is suffice. Vinegar? Unheard of to be honest.
Actually , the acid in the vinegar imparts a slight tooth to the brass. Not unheard of. What I do not know is how long is too long.
I have not done it but have thought about if for the reason mentioned by clauze, I probably would not leave it in vinager for more than a minute or two. I liken it to annealing the photo etch, make it more valuable to bend, the acidity gives the paint something to grab hold of.Unfortunately I forget to do both but have NEVER had an issue with paint sticking. Do however prime the entire model as sometimes my photo etch has a different shade than the surrounding plastic.
I just use a little hand soap a very soft tooth brush and a super light touch to clean p.e.
What the vinegar does is often called a conversion coating. Paint does not adhere well to pure metals. Conversion coatings are those whose chemicals convert the surface of a metal to a compound. Of course, air itself oxidizes many metals, but the oxides of many metals are not that great as a base for paint- the oxide does not stick well enough to the metal beneath it.
Vinegar is acetic acid, which really etches and converts the metal surface. However, most vinegar has a lot of impurities in it that are not that great. Used to be, photographic stop baths were widely available and were much purer form of acetic acid. Pure acetic acid is harder to find these days, but is better if you can find it. By pure, I mean just the acid and water dilutant. Literally pure acetic acid is very strong and a bit dangerous- well diluted acid is fine.
Brass blackening solution works well, and is available at many hobby shops. The resulting surface often is kind of flakey, and I recommend burnishing to get the residue off. If you need a black color, you are done after the blackening, but the thin black coating that remains will prime and paint well for other colors.
Some of the good metal primers contain chemicals that create such a conversion as part of the priming. However, it turns out that some of those compounds are carcinogenic, so those primers are not readily available any more.
Ditto that here.
But that was an interesting question and I found Don’s comments (amongst others as well) enlightening.
One thing NOT to do-don’t ask- is to wipe it with a soft cloth.
Generally, I don’t bother, same as I don’t wash the plastic, and am not aware of problems.
I have heard of that before but I just install and paint as the other parts and don’t have a problem.
Mike
I don’t know how to reply to everyone on here so here goes. Thanks to all who replied, it amazed me how quickly I got responses from all over the world. I got good info. This is my first experience with pe so I wanted my hand held. Working on a dio w/Jeep, Sherman, motorcycle and a dead PAK40. I’ll post pics when it is done. Again, thanks for your help.
Paul N.