Any ideas on how to prep and paint to use. I don't want this stuff to fall off in big sheets. This will basically be like painting aluminum siding. It's a prefab shed and it's already painted. I am going to pressure wash the old chalky paint and lichen and moss off of it. Do I need to prime it first, or just get a paint that is listed for aluminum siding type applications? Would this just be an outdoor latex paint? Barn paint? I haven't gone to look at paint options at Lowe's or online yet. Just looking to see what some folks say here.
Never personally done a building like this but the way we deal with aluminum at our industrial paint/blast shop is (if we can't blast it due to it being too thin) use an etch primer then your top coat over that. Aluminum can be tricky to work with and I know exactly what you mean with paint coming off in sheets. Coatings failures are most often a result of improper surface prep.
So assuming after I hit it with the pressure washer to get the mildew, lichen, and dirt off I still have paint left. I can't etch this, should I assume a good substrate on the painted surface since it's been there for 30-40 years and just go back with a quality outdoor, possibly a metal paint?
Yeah, if the paint is still adhered you might as well just go over it, no sense in doing much else besides that. If you have a better paint store local to you (PPG, Sherwin Williams, etc) I would buy from there. At least at places like that, you will have people who can actually tell you what is best and how to apply. Places like Home Depot or Lowes really aren't that knowledgeable on stuff like this.
I've painted vinyl siding with very good results...the paint I used said it would do aluminum siding too...its all about the prep work...just do as the paint manufacturer recommends and I bet it will work fine.
If it’s a steel shed like mine they are not painted to last it’s actually just primer from the factory. I have painted two of them and it held just fine after a good wash and degreesing. We used Rustoleum enamel with good results. I plan on doing ours soon as well. If you really want to do it right paint inside too to stop the air from causing so much rust on your equipment when the outside and inside temps vary and cause moisture.
I have aluminum siding on the house and have painted it twice. Owned the house for 28 years now. First time was about 1992 and again in I think 2017. Never had any peeling issues just weathering and fade. Both times I cleaned it well with a good deck and house cleaner, long handle brush and pressure washer. First time I masked and sprayed it, second time brushed it. Both times I used just good latex satin exterior paint from True Value.
Yes... It was probably coil coated originally and has a chromate treatment under the paint. Get it really clean and it will be a good substrate to repaint regardless if it has paint on it or not as long as it's not peeling. Any good exterior acrylic will be fine. Primer is always a good idea, but probably not absolutely necessary if it has paint on it. SW makes an exterior coating that has some anti mildew properties if it's in an area that can attract mold/mildew. Good stuff.
