Weld Through Primer Advice

[MSGGrunt]

I'm lap/spot welding some panels back together after shortening my 79 series bed and do realize that I should use weld through primer in between the panels. Here is my question.... Is there a difference in quality between these products? I see they range from as low as $9.00 for Dupli-Color, $23.00 for SEM and $25.00 for UPol.

What is the difference between the copper primers versus the zinc primers?

I am hearing good things about the UPol weld through primer, but it is expensive. Anyone have actual experience with any of these?

SprayPaintDepot - Weld-Through Primers

 

[WarDamnEagle]

So you need what, 1 can? I would buy whatever I thought was the best if the difference was only dinner for two at Wendy's. Seriously, I am no expert but the one time I was welding on sliders and wanted/needed some weld through primer I went with the UPol. Why? Because every review said it was the best and I didn't think $16 was that much more considering what everything else was costing me. Did I mention that I hate rust with a passion?

Edit: I've also used a few SEM products and they've always been very good. I did go with the UPol but I'm sure the SEM would work very well also. I don't think I would go with Dupli-color.

 

[PAToyota]

I agree with WDE - you get what you pay for. Considering the price difference and how inaccessible things will be after welding, it seems like cheap insurance to use the better product.