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Good morning folks,

 

Today's problem for the wise patrons of Britmodeller is - I have been priming with stynlrez through my airbrush & then over painting with vallejo model air.  It looks great - until I mask it & spray a second colour.  When the masking tape is removed or the whitetac on occasions - it is taking the paint & primer off - right down to clean plastic.

 

  • new airifix kit (Bedford mwd)
  • thoroughly washed & dried
  • silverline 2 in 1 brush / 20psi / 4mm needle / 2 moisture traps / littlejet pump
  • primed in 2 thin coats - stynlrez
  • vallejo grey primer also tried as an alternative
  • painted in 2 thin coats - vallejo model air
  • drying time 30 minutes to 1 hour between coats
  • masking tape - tamiya
  • whitetac also tried as an alternative to tape
  • atmospheric conditions - 20 degrees c at all times

 

The result when the tape or tac is removed is the paint & primer lifting - right down to the bare plastic.  On closer inspection if you get a blade under a lifted area it pulls off almost like a stretchy plastic film.

 

This first happened a couple of weeks ago with the vallejo / whitetac combination on some plastic food containers I was using for practice with the brush - before moving on to ruining a real model.  I initially put it down to the fact that the food containers may have some kind of coating that the paint didn't want to stick to - but I moved to stynlrez as a precaution - as it has rave reviews all over the forum.

 

Now I have the same problem with the tamiya tape on the airfix kit.  Previously I was rattle canning using humbrol cans & using tons of masking tape or whitetac & I never had a problem with paint coming off - EVER!!! :(

 

Any ideas would be gratefully received as always.

 

PS - I'm not going to let it spoil my day :) this is too much fun.

 

Thanks in advance,

Steve

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Well I have never heard of this Stynlrez stuff (I only use enamels and never use primer except for Alclad) so I put the name into google and the very first link on the list was someone complaining about masking having lifted the stuff, and the paint on top of it right off. Perhaps a thicker coat of primer would resist lifting better but I would guess it simply doesn't bond as well as a solvent based primer to the plastic

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44 minutes ago, Beardie said:

Well I have never heard of this Stynlrez stuff (I only use enamels and never use primer except for Alclad) so I put the name into google and the very first link on the list was someone complaining about masking having lifted the stuff, and the paint on top of it right off. Perhaps a thicker coat of primer would resist lifting better but I would guess it simply doesn't bond as well as a solvent based primer to the plastic

WOW - maybe it's not me?  But I did have the same problem with the vallejo primer too.  Maybe it is water based primers in general then?  the problem is - I need an "odour free" solution - working right in the middle of the house.

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Ideally you need to leave it 12 to 24 hours to cure properly.

 

Whilst it says that it is dry in 30 to 60 minutes, it has not cured properly so this may be why it is lifting after masking. I have recently finished an Airfix Shackleton using Vallejo primers. Having researched the problems other have had with this, and also needing to thin it a bit before airbrushing, I left it almost 24 hours before spraying the next coat. And then another 24 hours before the first coat of paint. By doing this I did not have any issues with the primer lifting. The paint I used on top of the primer was Tamiya acrylics thinned with their own thinner. The Vallejo was thinned with Ultimate thinners at a ratio of 25% thinner 75% primer. I used Tamiya masking tape throughout, and didn't have any paint or primer lifting at all at any stage (and believe me it's a substantial kit even at 1/72). I sprayed 2 thin coats of white primer, 3 thin coats of gloss white paint, (masked) and then 2 coats of XF24 to act as dark sea grey. with about 12-24 hours between each coat. When the masking was removed, no paint lifted.

 

Hope this helps.

 

 

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I am guessing that the coat may be just too thin. A review I have read today of the stynlrez stuff says that it was 'airbrush ready' from the bottle and not meant to be thinned although the reviewer says that he felt it was almost too thick to spray with a 0.4 needle and nozzle. If the coat is too thin (this applies to enamels as well as acrylics) then it will be porous and solvent or water will be able to get between it and the base plastic breaking the contact between coating and surface plus it won't have the film strength to resist being pulled up off the base plastic. Water based coatings and enamels don't bond with the plastic the way a solvent based primer does and so rely on contact and film strength to resist lifting.

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3 hours ago, Beardie said:

I am guessing that the coat may be just too thin. A review I have read today of the stynlrez stuff says that it was 'airbrush ready' from the bottle and not meant to be thinned although the reviewer says that he felt it was almost too thick to spray with a 0.4 needle and nozzle. If the coat is too thin (this applies to enamels as well as acrylics) then it will be porous and solvent or water will be able to get between it and the base plastic breaking the contact between coating and surface plus it won't have the film strength to resist being pulled up off the base plastic. Water based coatings and enamels don't bond with the plastic the way a solvent based primer does and so rely on contact and film strength to resist lifting.

Well it certainly sounds like you know your stuff Beardie - thanks a million for the input - it sounds like I need a solvent based primer...

 

Any recommendations for a solvent primer that has these selling points...

  • Low odour
  • Airbrush ready (no thinning)
  • Easy cleaning of the brush (with what)

I know I'm a pain - but "girls just wanna have fun" as Cindy Lauper would say :lol:

 

Thanks a million - Steve

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Unfortunately there is no easy answer to that. All the solvent based types are pretty smelly and also require smelly solvents to clean the airbrush afterwards.

When it comes to acrylics the paint film is generally a lot weaker than with enamels and, as far as I know, if you want tough the best answer is rattle cans of car type primer.

 

As I say I use enamels which have a much tougher paint film and so need no primer at all but requite a solvent like white spirit, turpentine or 'Low odour' thinners (available from art shops) to thin and clean up.

 

Perhaps someone from BM's Acrylic using fraternity can weigh in here with a solution?

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Yeah couple things going wrong there, as someone said perhaps not waiting long enough between layers and also thinning it. I presume that what '2 thin coats' means about the stynylrez? With these thin coats was the plastic completely covered? Also with that time frame the surface may be dry but the underside against the plastic won't be hence the lifting. Especially when it all gets damp again from spraying the colour coats. I think the main problem here is patience without trying to sound harsh obviously. 

 

Stynylrez doesn't need to be thinned. I spray it out of the bottle with a 0.3mm fine. Fair enough you have to pull right back on the trigger use a higher than normal psi. Don't be scared, it will look thick when it goes on, but shrinks back tight once the water has evaporated. I use a hairdrier to speed up the drying. It's pretty hard once cured proper. 

 

 

 

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3 minutes ago, Tony Oliver said:

Stynylrez doesn't need to be thinned. I spray it out of the bottle with a 0.3mm fine. Fair enough you have to pull right back on the trigger use a higher than normal psi. Don't be scared, it will look thick when it goes on, but shrinks back tight once the water has evaporated. I use a hairdrier to speed up the drying. It's pretty hard once cured proper. 

Hi Tony - thanks for coming back.  For the record I haven't been thinning it - it is described as airbrush ready - which is what I really found appealing about it.  I went for it after you offered me some advice in another thread about Vallejo model air paints and metallic finishes.

 

I will increase the psi and apply thicker coats on some test plastic and see if the shrink back tight method works.  it really needs to - I do a lot of masking :)

 

thanks for your sound advice again - Steve

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Ok then mate it must be the thin coats you put on. As is if its too patchy/not uniform nor thick enough then it will struggle to stick to itself. Especially if not left to dry for long enough. 

 

Solvent type primers 'bite' into plastic so you can dust them on & spot prime. 

Will acrylics there isn't that bond so I think they need to be more like a skin that wraps all the way around so it can hold onto itself if that makes sense? 

 

Practice on some scrap first. Too thick and then with too much heat too fast will make it crack/split 👍🏿

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Cheers Tony - thanks for the support matey - most appreciated - Steve

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  • 2 weeks later...

...just invested £6.49 in Halfords grey primer spray.  As per everything in my life - it wasn't simple.  I get to Halfords and find there are TWO choices - a quick google on my phone - 'Halfords grey primer - britmodeller' - result - people recommending both types - you couldn’t make it up :doh: Anyway I chose the one that simply said grey primer as opposed to the one specifically for plastics - as it said 'hard plastics' - the one I got simply said it was ‘an acrylic formula’ - which sounded safe.

 

Having got home and tested it on my latest 'masterpiece' it seems a lot like the Humbrol rattle cans I have used in the past - but you get a lot more for your money.  I will say it seems to be less smelly and with the extractor on - the feint odour was gone in a couple of minutes.  Also it seems to have levelled beautifully – even where I sprayed on too much – a hazard with cans – no ‘real’ control and a real PITA :lol:

 

I still see this as a major step backwards – but I just want to get on without the risk of the primer peeling again on a ‘busy’ camo scheme.  It’s only a temporary step back though – as I will ‘crack’ the airbrush primer problem – trust me. :)

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I believe you can buy Halfords Primer in a tin for brush or spray gun painting. Even more mls for yer money. Thin it as required and spray thru an airbrush. For undercoating/priming I recommend using a cheap Humbrol or Badger exterior mix airbrush

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6 hours ago, BIG X said:

...just invested £6.49 in Halfords grey primer spray.  As per everything in my life - it wasn't simple.  I get to Halfords and find there are TWO choices - a quick google on my phone - 'Halfords grey primer - britmodeller' - result - people recommending both types - you couldn’t make it up :doh: Anyway I chose the one that simply said grey primer as opposed to the one specifically for plastics - as it said 'hard plastics' - the one I got simply said it was ‘an acrylic formula’ - which sounded safe.

 

Having got home and tested it on my latest 'masterpiece' it seems a lot like the Humbrol rattle cans I have used in the past - but you get a lot more for your money.  I will say it seems to be less smelly and with the extractor on - the feint odour was gone in a couple of minutes.  Also it seems to have levelled beautifully – even where I sprayed on too much – a hazard with cans – no ‘real’ control and a real PITA :lol:

 

I still see this as a major step backwards – but I just want to get on without the risk of the primer peeling again on a ‘busy’ camo scheme.  It’s only a temporary step back though – as I will ‘crack’ the airbrush primer problem – trust me. :)

 

I've used both Halfords types without issue. Once you learn the spraycans 'personality' it becomes second nature and oh so quick to prime an entire model. I find a light wet sand with 2500 grit sandpaper before painting gives a lovely smooth finish.

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6 hours ago, Black Knight said:

I believe you can buy Halfords Primer in a tin for brush or spray gun painting. Even more mls for yer money. Thin it as required and spray thru an airbrush. For undercoating/priming I recommend using a cheap Humbrol or Badger exterior mix airbrush

That's really interesting as it happens - I have seen these tins - they could be awesome - has anyone tried the tins...

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48 minutes ago, Avgas said:

 

I've used both Halfords types without issue. Once you learn the spraycans 'personality' it becomes second nature and oh so quick to prime an entire model. I find a light wet sand with 2500 grit sandpaper before painting gives a lovely smooth finish.

Oh - I'm 'very' familiar with rattle cans and their 'split personalities' - that why I invested in an airbrush ;) :doh: 

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6 minutes ago, BIG X said:

That's really interesting as it happens - I have seen these tins - they could be awesome - has anyone tried the tins...

yes [not me] but you'd need to search thru the hundreds of WiP and GB builds to find out who.

afair - no difference in results to using the rattle can, just better control over it

Halfords and any automotive primer will have a heavier grain than a model dedicated one; a light  rub down with micromesh, fine w&d or just a bit of denim cloth smooths it even nicer

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...well the halfords has settled and dried a treat - time to add the SKY S in the morning and then real fun starts - mask the sky and add dark earth.

 

Then I've got to mask the dark earth to add the dark green - but this is where everything has gone to s... in the past -  when I remove my masking - let's hope the halfords is better than the vallejo or stynylrez - which both peeled like stretchy plastic bags - I don't think I'll sleep too well tonight - the excitement is killing me :lol: WHAT AN EXCITING LIFE I LEAD ;)

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I had the same problem with Vallejo paint (brushed) over Tamiya white rattlecan primer on a 1/72 C-130 and the same problem with Vallejo on top of Vallejo primer (again brushed.) I could run a fingernail over the model and the paint would crackle up underneath it.  Finally, put everything away for a week and had to do much repair work.  Yes, I did wash the models with Polyprep before starting. FYI. Cheers

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   hi ALL,

 

                          can't be bothered goin thru the Q 'n 'A's ...so anyway.

 

            Wot is the Brand?,....could be not pure Styrene and nuthin' sticks / glues to that !

 

           Current "Snap Kits " are made from " Wot Ever Rubbish "  and cannot be Glued by Poly Glues.

          ..only Supa Glues / Araldites ....if you lucky !

                                                                      Geoff

                                                                       g.g.m.s  !

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UPDATE - After coats of sky s / dark earth / dark green - lots of tamiya masking tape and whitetac 'worms' - the 'big peel off' took place this morning on my Hurricane - just before leaving for work...

 

RESULT - No peeling paint - the Halfords primer has done it's job - feeling good - mojo restored :thanks: everyone - team hug time :grouphug:

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2 minutes ago, Tony Oliver said:

Glad to hear it! 👍🏿

Thanks Tony - I have been 'in a very dark place' with this problem and everyone's support and ideas have kept my spirits up.  I do intend going back to airbrush primers - but I just needed to 'get something built' and this has been a big confidence booster for someone new to airbrushing.

 

Cheers - Steve

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  • BIG X changed the title to Primer peeling off

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