POR-15 Engine Enamel

[sseebart]

I'm planning to use this to repaint my motor, which is out of the car. Strange directions on the can--it says for professional use only, but has no instruction for spaying. I'd like to apply this using my HVLP sprayer. Anyone else tried that with this product?

~Steve

[Alan H. Tast]

I've used their gloss black engine enamel on my '63 - painted cast metal components with it (block, heads, water pump, intake manifold) 11 years ago with disposable foam brushes. Heads need to be touched up periodically at the ears as it will burn off, but everything else has been holding up real well. Sheet metal components like valve covers, air cleaner, and aluminum castings (i.e. front cover) I used spray-bomb enamels. Search to see if you can find a website for POR-15 for thinning/spraying directions, as POR-15 is very finicky when it comes to reducers.

[sseebart]

I've used their gloss black engine enamel on my '63 - painted cast metal components with it (block, heads, water pump, intake manifold) 11 years ago with disposable foam brushes. Heads need to be touched up periodically at the ears as it will burn off, but everything else has been holding up real well. Sheet metal components like valve covers, air cleaner, and aluminum castings (i.e. front cover) I used spray-bomb enamels. Search to see if you can find a website for POR-15 for thinning/spraying directions, as POR-15 is very finicky when it comes to reducers.

Thanks, Alan. I can see that a brush would be fine on the cast elements, but I want to spray the whole thing at once. I did purchase their metal prep for the sheet metal parts. It appears to be mostly phosphoric acid to etch the metal and eat away at the rust.

Their website and spec sheet are silent on the matter of spraying, except for specifying thinning (max 20%). A further search yielded little, most of it contradictory. The can says it's mostly mineral spirits, stoddard solvent (whatever that is) and pigment, so I may just thin a bit out and try a test spray.

I'm a little surprised that you had some burn off, as it's "guaranteed" not to do that. Color me shocked.

~Steve

[Alan H. Tast]

Their cast iron/manifold paint for the most part has held up, but I think the combination of the exposed surfaces of the exhaust manifold-to-cylinder head "ears" and different cooling rates contributes to the breakdown of the paint at that kind of location. I didn't put much thought into claims of "won't burn off" as I've seen applications of it prior to ordering and expected such to happen. All it takes to "fix" is a small foam brush dipped into the paint can and wipe on the ears - easy touch-up prior to going onto the show field.

BTW, since I applied the gloss black enamel in '05 I have learned that the original finish used on engine long blocks (heads, intake manifold, front cover, water pump, oil pan, crankshaft pulley/harmonic balancer, etc.) was more of a semi-gloss finish through '64 and had a more-glossy sheen for '65, based on descriptions and part/mix numbers I've researched. I wouldn't consider it a deal-breaker, especially since the glossier finish would be easier to keep clean and over time would dull down due to exposure to heat. And now that this has been discussed, it's time for me to touch up my engine paint.

[TroublesChild]

I realize that the original thread I am replying to here is several years old but I get asked about this quite frequently on the sites that I belong to. It seems that although Por15 is one of the more available engine enamels across North America it does not come with instructions for spraying. The spraying of their engine enamel calls for the same process as for their Rust Preventative Paint and Top Coat. Make sure that the surface is well cleaned to remove all grease and deposits and bare metal is washed down with metal prep. Make sure that the surface is dry and free of any solvent wet spots and they DO NOT recommend the use of primer on bare metal spots. First stir the paint thoroughly with a clean stir stick (preferably a metal one available from most automotive paint stores). Usually the paint when first opened can be sprayed as it comes in the can. If it has been sitting in a partially used can it may require some reduction to spray. Mix only what you figure that you will use, reducing the paint 5% with Por15 paint solvent (part# 40401). This works out to 3/4 of an ounce per pint of paint. I prefer to use an HVLP touch up gun with a 500 ML cup for painting engines as it allows better paint control and is small enough to have good control in the awkward places. Use 30 to 35 pounds pressure at the spray gun for a standard gloss and 20 to 25 pounds for a low gloss surface. Remember that the longer your air hose the more pressure drop you have so use a guage at the gun rather than going by the pressure at the compressor. Spray the paint in thin coats allowing it to dry until you can drag your finger over the surface without marking it (usually 4-5 hours). You will find the second coat will cover far better than the first coat. usually 2 coats will do the job quite well. Apply coats ONLY until you get an even color. Too much paint will cause cracking, peeling and discoloration after very little engine operation (If enough is enough more is NOT better). Clean the spray gun completely immediately after use (yes this means between coats as well as when done) as it will plug the gun and be almost impossible to clean if left unattended. I always recommend that any unused portion of the can be stored in a refrigerator between coats and afterwards as the paint is air activated and even the air in a partially filled can will cause severe thickening, hardened spots and cause it to go stringy.