Paint or Powder Coat Chassis

[Sherman Kaplan]

Went to visit the chassis for my 73 Special.  It has been blasted and is ready for repair of the rust holes.   The question is whether to have it painted or powder coated.   I'm aware of many of the pros and cons of both methods, which makes choosing even harder.  What is the consensus of the group?
Also, what color, gloss or semi gloss?  I think originally it was semi gloss, but after 45 years it was hard to tell.

Thanks,
Sherman

[andy harwood]

FWIW, After blasting, I used POR, gloss black, as what was in stock at parts place. The inside cavities, used Eastwood internal frame coating.

[BDA]

I used gloss IMRON polyurethane paint on mine but if POR15 was available when I painted my frame, I hadn't heard it. I think the original paint was pretty cheap (like most things on Lotus cars at the time) - buddies of mine who had English race cars in the mid 70s found the epoxy paint on them to be very good so it seems that better paint was certainly available.

I think Andy has the right idea. Gloss is a bit easier to keep clean but gloss or semi gloss is a personal choice. I've heard of some issues with powder coating relating to moisture retention but you probably know more about powder coating than I do. I've heard nothing but good things about POR15.

[Certified Lotus]

I powder coat all my frame off restorations. Why? Powder coating will adhere to places you can’t reach with a brush or spray gun. Most of these cars are not daily drivers and probably don’t even get driven in the rain (unless taken by surprise). I’m not worried about water getting underneath the paint.

Just my 2cents worth.

[gideon]

I wish I knew the answer - the more I read about this topic, it seems the less I know.  But, I do know that powder coating can fail badly with with corrosion under the coating.  So, if you go that way you want to be sure that the preparation, materials and processes are top notch. 

Consider a zinc-rich primer.  The federal highway administration published this summary of their experience with zinc rich primers on bridges :

https://www.fhwa.dot.gov/publications/research/infrastructure/structures/bridge/zinc.cfm

It's well worth a read.  This is a good quote :

"The primary performance difference between zinc-rich coating systems and systems based on barrier or inhibitive protection is the resistance to disbondment and underfilm corrosion at holidays or defects in paint films and at corners and edges of structural steel members."

You might be able to get a zinc-rich powder coating, followed by a top-layer power coat.  I saw that done on Wheeler Dealers, TVR episode.

For the chassis, my vote is for paint.  It's easier to repair, and today's two-part paints are pretty tough.

[Certified Lotus]

I will add that you must media blast the chassis, not a wire wheel, to use powder coat effectively.

[jbcollier]

Powder coating is just another way of applying paint.  In the end, you have a painted product either way.  How successful the process is depends more on prep and the product chosen.  Decorative paints don't hold up well to outside exposure.  HD industrial coatings work much better but don't give aesthetically pleasing results.

I used an industrial painter who specializes in painting equipment that live a hard life outside.  He used a special wand to get inside the chassis.  Turned out very well.  Proof is in the pudding though.  Ask me again in ten years.

More important than the painting method chosen is regular applications of a non-hardening rust preventative.

Regarding the comment that powder coating gets into nooks and crannies better.  Maybe, but only if that inaccessible space has been blasted properly, unlikely.

[gideon]

JB - which non hardening rust preventative product(s) would you suggest?

[jbcollier]

I like Wurth products.  I use their "Cavity Protection Spray".  But, it's not a big deal what you use as long as it stays viscous.   I worked at a Citroen shop and we would save the old engine oil and spray it inside the door and body cavities.  WHAT A MESS !!  But they didn't rust.

[Rosco5000]

My 0.02 cents worth.  I wouldn't use POR15 on my Lotus I experimented with it on my 4X4, followed all the prep instructions flawlessly and it flaked in 6 months.  I had high hopes.  The last mini shop I worked at swore by an industrial epoxy primer with a high quality paint over top for all subframe and unibody work..  My friend restoring muscle cars and owns an industrial supply shop also swears by this combination.  That will be my choice going forward.  Endura paints are from the industrial world I understand and I have seen them have great show quality finishes but I don't know if they are still available in the world of low VOCs.
Ross

[dakazman]

Sherman,
   The first thing is to get a good self etch primer on it or an epoxy for bare metal if your painting. I do not powder coat but would like to learn . Living in florida , I do not have to worry about street salt eating my frame. When I lived in NJ we used zbar on undersides of cars.  I just used paint and rustoleum gloss black.
Dakazman