Rustoleum Hammered Paint - To prime or not to prime?

[mickyd]

What's the users recommendation for whether or not to use primer when painting the sheet metal and cast aluminum SS parts using the spray cans? The front of the can says no primer needed yet instructions on back says primer recommended on bare metal.

I saw a difference in texture when painting a side by side sample of primed vs. unprimed sheet metal. You can see it here (http://www.shopsmith.net/forums/showpost.htm?p=32239&postcount=20).

[bucksaw]

I always prime just about everything I paint, especially metal.

[mickyd]

I wanted to update this thread with some info I got off the Rustoleum website regarding priming. The technical data sheet (http://www.shopsmith.net/forums/attachment.htm?attachmentid=4412&d=1241796205) recommends not to use primer (in the surface preparation section) whereas as mentioned in my first post, the actual spray can label (http://www.shopsmith.net/forums/attachment.htm?attachmentid=4413&d=1241796217) indicates primer recommended on the back of the can but also says no primer needed on the front of the can!!! I guess this means flip a coin???

I tried both methods when I did my Greenie (http://www.shopsmith.net/forums/showpost.htm?p=37606&postcount=293). The sheet metal belt cover and motor pan were unprimed and all the other painted parts were primed with self etching primer. I should have tried no primer on one of the cast aluminum parts just to see if there would be a longevity issue but.....didn't think of it. Next time for sure.

At this point, I can only say that my experience on sheet metal test sprays with spray speed constant, the texture of the paint varies when applying to primed or unprimed surfaces as shown in this other post (http://www.shopsmith.net/forums/showpost.htm?p=32239&postcount=20). You'll notice the primed left side of the panel has very little texture and the right side has a heavier texture. In order to get the unprimed sheet metal to match the primed, the application had to be heavier (slower speed). Unprimed has to use MORE PAINT to get good texture. Hopefully, this wasn't the motive of Rustoleum's marketing / engineering group for increasing paint sales.

I guess the bottom line to this thread at this point is.....don't know the longevity effects of priming vs. not BUT I do know the effects on texture. Only time will answer the question regarding longevity. My comparison will ultimately be the sheet metal base legs (primed) as compared to the Belt cover and motor pan (unprimed). To get the texture right, you need to make sure to do test sprays on an similar base substrate (primer or not).

p.s. To get your hands on cheap sheet metal, keep your eye on Craigslist. In populated areas, people are giving away file cabinets / desks all the time.

[JPG40504]

I wanted to update this thread with some info I got off the Rustoleum website regarding priming. The technical data sheet (http://www.shopsmith.net/forums/attachment.htm?attachmentid=4412&d=1241796205) recommends not to use primer (in the surface preparation section) whereas as mentioned in my first post, the actual spray can label (http://www.shopsmith.net/forums/attachment.htm?attachmentid=4413&d=1241796217) indicates primer recommended on the back of the can but also says no primer needed on the front of the can!!! I guess this means flip a coin???

I tried both methods when I did my Greenie (http://www.shopsmith.net/forums/showpost.htm?p=37606&postcount=293). The sheet metal belt cover and motor pan were unprimed and all the other painted parts were primed with self etching primer. I should have tried no primer on one of the cast aluminum parts just to see if there would be a longevity issue but.....didn't think of it. Next time for sure.

At this point, I can only say that my experience on sheet metal test sprays with spray speed constant, the texture of the paint varies when applying to primed or unprimed surfaces as show in this other post (http://www.shopsmith.net/forums/showpost.htm?p=32239&postcount=20). You'll notice the primed left side of the panel has very little texture and the right side has a heavier texture. In order to get the unprimed sheet metal to match the primed, the application had to be heavier (slower speed). Unprimed has to use MORE PAINT to get good texture. Hopefully, this wasn't the motive of Rustoleum's marketing / engineering group for increasing paint sales.

I guess the bottom line to this thread at this point is.....don't know the longevity effects of priming vs. not BUT I do know the effects on texture. Only time will answer the question regarding longevity. My comparison will ultimately be the sheet metal base legs (primed) as compared to the Belt cover and motor pan (unprimed). To get the texture right, you need to make sure to do test sprays on an similar base substrate (primer or not).

p.s. To get your hands on cheap sheet metal, keep your eye on Craigslist. In populated areas, people are giving away file cabinets / desks all the time.


How's THIS for an explanation of the label/tech info "CONTRADICTION" regarding use of 'PRIMER".

1) The Tech Info is written/created by folks who KNOW of what they speak(they know what they are talking about).:)

2) The label is created by Marketing by folks who know a LITTLE about what they are talking about(Not what is, but what isn't).;)

The label refers to BARE wood or metal. The tech info seems to be referring to previously painted objects. Yes the label info jumps around(must have been written by a female).:eek:

OOps! I wrote this like a PM! Others would not understand some of the jabs. I am letting it post as is. Let the chips fall where they may.

[mickyd]

................Yes the label info jumps around(must have been written by a female).:eek:

OOps! I wrote this like a PM! Others would not understand some of the jabs. I am letting it post as is. Let the chips fall where they may.

Eyyyy..... and a brave man you are!!!

[etc92guy]

imho.....prime if it's wood so the surface doesn't swell from the moisture of the paint. prime if the metal is so smooth that the paint won't grip. no priming necessary if you have a metal surface that the paint will grip.

The hammered line was formulated to cover damaged metal surfaces. The textured surface is supposed to hide surface defects.

[judaspre1982]

Micky D , On your test piece of sheet metal, how many top coats were applied? I agree with--ect92guy--for the most part. I cant say for sure that priming metal surfaces when using the Hammered finish is needed or not, but I can give you my observations. My pre-restored Greenie looked much like Mikes after being stored in a non-climate controlled atmosphere for approx 15 yrs. The previous owner had used it in his basement workshop from 1955 to 1993. His basement was heated and cooled year round. When I brought the machine home, (1994) all painted surfaces were solid, no flaking. After the long storage, the paint on all cast alum parts was flaking severely, while the sheet metal painted parts were still solid. When removing the flaking paint from the alum, it did not appear that primer was used at the factory. This was evident when inspecting the flakes. The color of the flake was the same on both sides. I would think if primer was used it would be some other color on one side. Why did the paint fail only on the aluminum parts? No evidence of primer could be seen on the sheet metal parts , but the paint did not fail. I assume the factory paint process was the same for both metals. When I painted my machine, the alum parts were taken to bare metal and the sheet metal was sanded smooth. I used white metal primer on all bare metal surfaces, which were scuffed and cleaned before spraying. Only one thing that was cast alum did not get primer, that was the tailstock. I used two coats of primer, immediately followed by three top coats. I allowed a good two weeks of cure time before any rough service to parts. After some projects and the normal scuffs and abrasions, I noticed that the paint over primed parts was holding up better. The paint on the tailstock ,when tested would scratch down to the metal much easier. These are only my observations and procedures ,not recommendations.For me, any future paint jobs, whether they be wood or metal will always get a good coat of primer, especially aluminum. I am sure there are many posibilities why the paint failed on the alum parts. Todays paints are very different then those from the 1950s. I have seen many manufacturers make recommendations for their products without enough feild testing, which is where the true testing takes place. Of the many brands of spray paints used over the years, I have been most satisfied with the Rustoleum Hammered Finish for durability.------Dave

[mickyd]

Excellent overview jp. I'm glad you mentioned about your aluminum tailstock not having primer and not being as chip resistant. Also glad you mentioned that the steel parts held up well as compared to aluminum since that is what I did on the headstock.....no primer.

It's very possible that Rustoleum recommendation for not primer applies to steel and not aluminum.

I has a more warm and fuzzy priming also BUT....I will test it out for myself.....just the way I am.......gotta know first hand!!!