[AMRadio] Painting experts - Vintage gear

[Robert Sauvan]

On 5/24/2013 2:55 PM, W5AMI wrote:

Brian,
I am by no means an expert, but let me give you a few tips I have used 
over the many years of spraying. Just a bit of background first might 
help. I have been spraying finishes for nearly 45 yrs sorry to have to 
say. I have sprayed automotive finishes and cabinet/furniture finishes 
for many years. The choice of finish many years ago was lacquer. Lacquer 
is difficult to get now a days but still can be found at some auto 
finish suppliers. Lacquer is very forgiving. Easy to work with. If you 
get a run in the finish it can be sanded out in very short time and 
resprayed almost immediately. One draw back is that it can become 
brittle in time and will get cracking to appear over time also.
Acrylic enamel is probably the best choice for a finish on radio 
cabinets because it is a bit more flexible and will not tend to get 
cracking as lacquer does. Your comment about the rattle cans is right 
on. Very difficult to get a uniform finish on large surfaces. The trick 
here is to put on numerous coats. Spray in one direction and then spray 
in the opposite direction meaning 90 degrees to the last coat. You must 
sand quite well between coats until you have sanded all of the orange 
peal on the surface and eventually you will have a very nice finish. 
Another trick is to get to your final coat and when you are happy with 
the uniform surface, sand again until all of the orange peal is gone and 
then buff the finish with a rubbing compound until you get the sheen you 
want. Then wax it with an automotive wax. Not sure if you want to take 
it this far. Depends on how particular you want to be I guess.
Thinning is a necessary thing depending on the paint you are using. The 
paint can will usually have the ratio on the label needed  to aquire the 
correct mix depending on the product you are using. Particularly if you 
are spraying it through a gun. I would stay away from water based 
finishes. They are inferior to any other finish and it has not been 
perfected yet. It might be OK if you have no other choice but I would 
stay away from it since the enamels available yet today are much better 
and you wont gain anything at all by using water base finishes other 
than being environmentally friendly.
I cant help you with the crackle finishes and I have never heard of 
adding Tung oil mixed with paints. I can relate to the difficulty of 
getting a wrinkle finish uniform with the spray can set up. I do believe 
though that there is a technique used where you spray a finish and then 
put it in an oven to get it to wrinkle. In the cabinet industry, which 
is the industry I am in, we use a special lacquer which we mix with the 
finish to achieve a wrinkle on cabinetry. I know wood lacquer is 
different than lacquer used on metal products but I would be bet there 
is a comparable formula for metal finishes.
I cant stress enough the importance of sanding. Sanding is the key to an 
excellant finish. This is the one thing  almost anyone I have ever 
talked to or discussed why they have a failed paint job is because they 
havent spent enough time with the sanding process. It is the key to an 
great finish.
I dont know if I have added more confusion to your question or helped 
you out. Hopefully I have helped you out. Let me know.

Bob-W0YBS


> I redo a lot of vintage rigs, and I always try to paint the cabinets if I
> can.  I have just about given up on rattle can spray due to small fan size
> and lack of nice uniformity on the larger cabinets.  I have a commercial
> sprayer I want to try (except for setup and cleanup), and wonder if anyone
> on the list can tell me what type (not brand) of paint I should use on
> primered metal.  Must it be oil based, or with water based paint work
> well?  I also wonder about the need of thinning.  My spray tip is .015.
>
> Also, has anyone had any luck using Tung oil mixed with liquid paints to
> produce a good wrinkle finish?  If so, how much Tung oil should you start
> with in the paint?
>
> I hate the rattle can wrinkle paints.  It's been about 50:50 on success,
> unless it is small parts.  Large flat surfaces never give me a uniform
> cover of wrinkle.
>
> Thanks
> Brian / w5ami
>