Zahn Cup

[Andy]

Another thread (see compressor and gun) got into a long discussion about checking the viscosity of paint before spraying it. I thought I would post this for anybody that doesn't know what a Zahn cup is, since it is rarely used in body shops anymore.

Have a happy new year,
Andy

A Zahn cup is a device for measuring the viscosity (thickness) of a liquid. They come in different sizes, with the #2 size being the most common for materials like paint. It is used by dipping it into the liquid and timing the number of seconds it takes the liquid to drain through a hole in the bottom.
In a paint shop it is used to determine if a material is at the proper viscosity for spraying, thinning a material for spraying, or selecting the right spray gun/fluid tip/air cap combination for the material.

In my opinion, it is not needed with modern automotive paint products. Following the mixing ratios exactly as specified by the paint manufacturer is all that is needed. However, it can be useful for thinning an unknown material, such as a brushable enamal for spraying.

463

[MARTINSR]

All this talk about the zahn cup has brought back memories for me, good memories. The last time I used one was a good time in my life around 1978. I was 20, in love with my soon to be wife (who became an ex-wife) and working full at a restoration shop. Everyday I walked into a shop full of vintage cars, we specialized in model 40 Fords (1933-34) and I was painting full on show paint jobs day in and day out. It was a dream come true for a kid who loved cars. I sprayed who knows how many coats (hundreds-thousands?) of Ditzler lacquer (thats PPG for you young punks :) ) and I had the cup with a stop watch right there on the bench. As I remember it was a plastic, white plastic cup though, not that high tech aluminum one you have. :)

I mixed gallon after gallon of lacquer using it. I remember like it was yesterday clicking that stop watch. Funny thing is, I am damn sure that even then I was just going thru the motions, if thinned at 100% it was right every time, but I could be wrong. Sprayed three or four coats and sanded it FLAT to zero texture on every single square inch of the part, then sprayed three or four more. The first time a rep came in (thank GOD for the paint rep, without him we would know nothing about new products) with "Ultra fine" paper. It was 800 grit and what a HUGE improvement over 600 that was for buffing!! HOLY CRAP what an improvement! The first time I used it was on a little T bucket in Hugger orange. I just cound't believe how easy it was to buff those "Ultrafine" scratches out over the 600 scratches. WOW, what in improvement.

Yep, that was like a dream a hundred years ago me, my little wife, all black hair, and a zahn cup on the bench. :)

Brian

[Pot]

You didn't have to bring up memories like that.
The first complete lacquer job I did was on my 62 Impala SS convertible in 1965. I didn't have access to a buffer so I sanded it with 600 grit and hand rubbed it out using nothing but rubbing compound and DuPont No 7 polish. That took awhile.

[MARTINSR]

You didn't have to bring up memories like that.
The first complete lacquer job I did was on my 62 Impala SS convertible in 1965. I didn't have access to a buffer so I sanded it with 600 grit and hand rubbed it out using nothing but rubbing compound and DuPont No 7 polish. That took awhile.

LOLOL, the very first paint job I ever did was a lacquer job on my 64 Nova around 1975 or 76. I put five or six coats on it (white) and then proceded to rub it out by hand. :) I didn't get very far, I think the trunk lid was polished, that was it. But you know, it looked pretty good. I applied it pretty smooth and wet and it really didn't look too bad.

You know what really makes me sick is thinking of the 62ish Impala SS convert that we junked out. My brother bought it just for the motor. After the motor was pulled I remember he was screwing off and ran up hte deck lid and up onto the roof, falling thru it. :) Darn car was pretty straight too.

Brian

Now I am thinking, maybe the very first was my brothers chopped (did that too) Model A pickup that I painted in acrylic enamel (daytona yellow). God, how you forget stuff. How in the world could I forget which was first?????