Rustender

Is it necessary to wash rustender off before you prime with an etching primer?

I've never used this product. What I read about it on the net is rustender is a primer which would not need the etching primer over it. What kind of paint are you wanting to topcoat with? You would have to find out if the topcoat is compatible with rustender. Sometimes you can use a primer that is incompatible and the paint will peal off the primer.

I planned on using acrylic enamel.

Just today I received the quart of rust ender I ordered a week ago for a running gear I am bringing back to life. The label says to apply a "abundant first coat" to the rusted area and let dry for 15 to 20 minutes and then apply a second coat. Let dry for at least 24 hours but not more than 48 hours before applying a finish top coat without the need to sand or scuff up the rust ender. If you wait more than 48 hours before applying the finish top coat, "mild scuffing" to the rust ender is needed. If you wait more than 72 hours before applying the finish top coat, rust ender must be "very thoroughly sanded with a medium grit sandpaper before painting". Also the label says to topcoat with an oil based enamel. I planned to topcoat with an acrylic latex semi-gloss enamel suitable for metal surfaces and emailed the rust ender company to get their opinion. They told me my acrylic latex paint would be compatible with rust ender. Soooo, I will use a paint brush and apply 2 coats of rust ender and then 24 hours later I will apply my first coat of acrylic latex paint. Surprising to me, rust ender cleanup is soap and warm water. I thought it would be paint thinner. Hope this is helpful.

I've searched every bit of info on Rust Ender on the net and I don't believe I would use it for acrylic enamel without calling the company. They are more concerned with pushing the environmental crackpot rhetoric than giving information for the use of this product. All they say is the primer is suitable for paints made for metal.

Yes, I was skeptical also. I did email the company and they responded that my plan to use acrylic latex enamel would work over rust ender. I'll do it and, based on their assurance, expect it will work.