A support pole and bracket can be purchased for use with the Speedheater. I would build a work platform to get closer to the ceiling, and let the pole and bracket take the weight of the heater.

Another method would be have one person use the heater and another do the scraping.

The website has a video to demonstrate the proper techniques.


Mike

The heat gun works quite well. All the many layers of paint come off at once with putty knife. I think the galvanized metal helps distribute and hold the heat. The car had at least three interior colors over time. Thanks for the ideas. We have not tackled the Masonite yet.

The heat gun will also work on the masonite, but be very careful about the amount of heat and the sharpness of the blade - it can dig in.

And, as always, well ventilated workspace is very important. Lots of nasties come out in to the air when heat stripping, too.

dave

I have a saying... if your paint prep is worth $50, use $50 paint. IME, on this type of job, it's just a bugbear. There's no such thing as $50 prep. The stuff that is peeling is devilishly difficult to get off completely, and if you don't, it'll peel off later. It's a lot of tedious hand work, and it's practically easier to strip the whole panel. So there you are at good prep.

You have fairly soft materials - the masonite, and the zinc on the galvanized steel (which gives your corrosion resistance.) I would not use any kind of media blast. Nor would I use needle chipping, or any other impact type method. If you stick cheap paint on galvanized, it will fall off, because the galvanization will protect the steel from the paint. Galvanized requires special primer. So there you are at quality paint.

I would be hesitant to use aggressive scraping, or needle chipping. You're fighting paint that is very hard and well-cured, and possibly (but not necessarily) lead, so you don't want to make dust. If a heat gun works, cool, but watch out for digging into the zinc when you scrape. Chemical stripper would be good too, brush it on and cover it with thin 1-mil plastic to stop it drying out, so it penetrates instead. It may take 2-3 cycles because the stripper doesn't go on evenly, and there are "thin spots" where there wasn't enough stripper to fully penetrate. Yes I agree that I would expect any paint stripper, left a week, to simply dry out and become as hard as the original paint, so you'd have to fool around but I would start with an hour.

After that, you want to thoroughly clean the surface, then "scuff sand" it, e.g. with steel wool or a Scotchlite pad - the objective is not shaping or surfacing, but to break any glaze (e.g. on the galvanized) and provide a microscopically rough surface for the paint to bond to. Then lastly a wipedown with an appropriate solvent to remove the last of the dust and any chemical contaminants.

The next step is the primer. If you're dealing with a porous surface, a 2-part epoxy is superb, because it will soak deep into the substrate and then cure at normal speeds, as the epoxy cure does not require contact with air. The result will be a very tough surface ready for paint. You don't even need to be in a proper primer for this, the same trick will work with any reputable epoxy product that will soak in, from West System to Git-Rot... scuff sand and wipedown to remove the chemical "amine blush" from the surface of the cured epoxy.

Here is a page that talks about painting galvanized... http://www.galvanizeit.org/about-hot-di ... zed-steel/ As you can see, alkyds (the usual "oil paint" sold at hardware stores, e.g. Rustoleum) perform poorly on galvanized. It says polyamide epoxy primers are excellent. That is back to the same 2-part epoxy primer I talked abut for porous surfaces, e.g. Awlgrip 545 or Amerlock. Another option is "cold galvanizing coating", which is a paint resin with a very high amount of zinc solids in it, which acts like a galvanized coating, I don't know if that's available in a 2-part polyamide epoxy, but it would be slick if it was!

The neat thing about 2-part epoxies is that they will accept almost any topcoat.

Then finally a topcoat of your choice: again if your prep efforts are worth $50, use a $50 paint.

Robert,

Thanks for taking the time to write such a useful post. Should I thank the turkey for slowing you down. You have confirmed and extended many of my thoughts. Many creative folks at several museums have been teaching me how to paint but galvanized steel is a new one.

The URL you gave (American Galvanizers Association) is also very useful. I have written them with a couple of questions.

$50 prep for $50 paint. Isn't that a little dated? The other day I paid $91 for a quart self-etching primer and a quart of its catalyst for some prep work on aluminum and that's only part of the prep effort.

Hope you museum has a good holiday season.

Glad to help.

$50 prep / $50 paint... is basically a reaction to the railroad museums that put many weeks of back breaking labor into paint prep... and then... they slap $30 hardware store paint on it. And then, the paint job goes bad in 5 years and they must do it all again. Because of this I developed a philosophy of "spend money on paint commensurate with your prep." If your prep amounts to swishing a wirebrush across it (and I did that type of prep just last week)... don't waste "the good stuff" on it. Just use cheap paint. But when you bust your hump to do pride-class prep... then yes, you want to be using the same grade of paint that Boeing puts on the Dreamliner. The cost isn't prohibitive... doing the job 3-4 times because your paint didn't hold up, that's prohibitive.

If you value the real cost of the prep, the cost of high quality paint becomes inconsequential and it makes no sense to not buy a high quality, reliable product and apply it corrrectly. Just because volunteers don't get a salary doesn't mean they are of no value. I'm frequently surprised by the number of "leaders" who don't understand this......sort of like the "bake sale" funding model mentality.

dave