Prepping for painting a motor

[mr-asa]

So, I’ve got my QD-15 completely broken down and will be prepping it for paint later this week. Bead blasting it, then I’ll clean the dust off and do a final degreasing with something like naptha then I’ll be shooting it with primer.

Any recommendations? Anything to watch out for? Was going to let the primer cure for at least a week then shoot it with the correct paint. Is Reprotint the best option if I’m not looking to get something custom color matched? Sea Horse Green is the right color?

[wedgie]

There are different primers. Some have to be topcoated within a certain time frame or you have to sand to ensure good adhesion of the top coat. Not easy to sand the convoluted surfaces on many parts of an outboard.

[mr-asa]

I was planning on using zinc chromate, and from what I know of it so long as I apply coats while it’s still tacky, it should adhere fine.

Dad repainted Grandpop’s motor not long ago and used zinc chromate and roughly that process. It’s way too early to see how it holds up, but none of it seems to be failing.

[lloyd]

I don’t recommend using Naptha or any petroleum based product for degreasing or prep for primer. Just smears the grease around and creates numerous problems. Recommend cleaning with water soluble degreaser like Simple Green, Super Clean, Castrol degreaser, etc. Then clean and etch with Phosphoric acid and quick water rinse and quick dry.

Zinc Chromate primers are very hard to find, and very finicky about adhesion, film thickness, and compatability of topcoats. Self etching epoxy primer (like Dupont Variprime) or PPG/Ditzler DPE primer is much more reliable. SEM is also good and comes in an aerosol can, so it is easy to use.

[r-amp-d]

Mr. Asa

Excellent choice with Reprotint, I just met Barry yesterday for the first time at our meet in Detroit at Lockemans. I’m not at the painting stage yet on my Mark 55E restoration but I did pick up all the supplies I needed from him. Just remember when painting use only one manufacturer for the complete process. Barry is a class act in my book and I would recommend his products to everyone. Yes listen to Lloyd on prep work. Pics are posted of yesterday’s meet at Lockemans on the Great Lakes Chapter Website in the forum.

Travis

http://www.liquidassetsonline.org

[burt]

Make sure your primer and top coat chemistry match, then observe the "open time" specified by the primer chemistry. Degrease your hands or wear gloves when doing the final cleaning to avoid body oil spots that won’t take paint. Self-etching primer is a good bet in all my projects.

[chris-p]

I don’t use zinc chromate anymore either. Self etching primer seems easier to work with, and is better for you. Follow the reccomendations on the can! As Wedgie pointed out, if you wait too long to paint on top of the primer, you have to scuff it, and some spots can be difficult!

I find most of my work is in the prep, get her clean! It will save you time down the road. Have you seen this? Interesting reading.

https://conductorjonz.wordpress.com/201 … p-day-one/

[mr-asa]

So what sort of self-etching primer should I go with? And could I get some clarification on the issues with different chemistry paints? Do you guys mean enamel on enamel, or oil based with oil based, or what?

[wedgie]

Your safest bet is to buy all your paint from one supplier. There are alkyd enamels, acrylic enamels, acrylic urethane enamels etc. If I’m not mistaken "enamel" just means it is a hard finish like the enamel in your teeth.

Self etching primer for aluminum is a good first coat. you can get it in rattle cans from the auto parts store. with etching primers, you don’t want to get it on too thick. a thin even coat is preferable.

I have access to industrial coatings in my line of work (shipyard) so I use an epoxy primer with aluminum, and or bronze powder as the binder.The aluminum primer is a nice dull aluminum that can be left as is. As Lloyd said, I wouldn’t use naphtha as a degrease. Use simple green to get the majority of the oils off,then follow up with lacquer thinner or acetone, or brake cleaner in an arerosol can, as a final rinse. Then paint immediately after the final cleanup as aluminum oxides re form on the surface very quickly after you clean them off.

Here’s a ’54 cowling with the aluminum epoxy primer sprayed on using a turbine hvlp paint sprayer. Had to thin it out about 30 % to get it to lay down.

Here’s a tank with the bronze primer

[chris-p]

I buy all my paint from NYMarine, so they are compatible. Trouble arises when you start mixing suppliers as mentioned. If you buy from Reprotint, you will be ok too.

I do the same as Wedgie, degrease using Super Clean and pressure washer, then wipe off with acetone, then quickly spray on self etching primer. A lot of paint can be laid about half hour after self etching primer, and I usually lay about 3 coats of paint.

[Author]

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