Trouble with Army Painter Spray Undercoat (White)

[Big Insect]

I have been experiencing an 'issue' with spray undercoating some 28mm figures.
It started in the summer - I'd cleaned and washed (in detergent & water and then rinsed thoroughly) c.30 x 28mm foot figures. It was a warm dry day, not too hot or sunny - ideal for spray undercoating I thought.
So I sprayed them outside, in the same way I've done for years - using a can of Army Painter Spray undercoat, which is a brand I've been using for years.
I thought nothing more of it. Set them aside to dry and then 'horror of horrors' they all went 'bobbly'.
I've never had this before. I checked the instructions and the FAQ from Army painter online and guessed that maybe it was too warm/hot a day. Hey-ho.

So I cleaned the nozzle of the spray can - stripped the figures (in Dettol - my trusty go-to stripper) and started the same process all over again - but on a cooler day. I shook the can vigorously and for at least a minute - sprayed from c.20cm away - in multiple thin layers and waited.
But with the same 'bobbly' result 

At this point I was onto the 'Chat' help facility on the Army Painter website. They checked everything I'd done and then very generously refunded the cost of my can of spray - and I duly threw away the old one.
So I purchased a new can - but low & behold, I've had the same 'bobbly' issue all over again! 

It's a mystery - I appear to be doing nothing out of the ordinary from what I've done for years.
It's a great shame as I've always found the army painter spray so reliable.

Next step is to try some Army Painter 'black' undercoat spray - on different figures - to see if I end up with the same effect.
Somebody else suggested it might be an impurity in the casting metal (& these are figures from a new manufacturer) but that does sound a bit extreme. But I've cleaned & washed them 3 times now - so I am doubting that.
I will also be trying another brand of spray undercoat as well. Somebody recommended spray undercoat used for car repair (as it is designed to cope with various metals) - but does anybody have any thoughts, comments or suggested alternatives?

Cheers
Mark
 

[jimduncanuk]

I would try brush coating with a good quality white undercoat to compare results.

[Steve J]

I find Halford's own brand spray primers much better than Army Painter ones. I use a black primer, which is more expensive than the standard grey one IIRC. Worth every penny though IMHO. You can get etch spray primers too that will bind with the metal, which is what they are intended for. Hope this helps?

[Duke Speedy of Leighton]

I use Halfords white

[Orcs]

On the rare occasion I use spray cans I shake them vigorously for at least 2 minutes. Then I spray inside in the loft. Never had any issues, but I only use Halfords sprays.

[Big Insect]

Thanks all

I think I shall try the white undercoat paint option 1st - as I on a tight schedule - needing to get the army finished for a competition in early Dec. These 30 figures represent the last couple of units and some command bases.

I think I'll then try the Halfords option as we have a branch within walking distance of home.
I use white for my lighter troops - and as this batch are mainly flesh and loin cloths, that seemed sensible.
I reserve black mostly for later figures (dark age & medieval) with a lot of armour or my 15mm stuff - as I mostly drybrush those. Although I did try a brown spray with some ancient Germans and that was very effective.

Anyway - it just seems a shame that a long trusted supplier appears to have fallen by the way-side. But 'needs must..." and I dont have long (in relation to my painting time) to get the whole army painted and then based.
Hey ho.

Cheers
Mark