Undercoat causing 'blotting'
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Thread: Undercoat causing 'blotting'

  1. #1

    Default Undercoat causing 'blotting'

    Today I came across something I've never seen before so I wondered whether the great minds (and even maybe the slightly less than great but above average minds) could give me some insight.

    I sprayed up a mini using GW white undercoat as per usual, never having had any problems in the past, and whilst I know a lot of folk prefer grey primer, I'm a fan of white, humour me.

    It then came time to apply the first colour. I work with very watered down paints using the (to coin the french) 'juicing' method. When the paint first touched the undercoat it blotted. That is to say it dispersed for up to a millimeter either side of where the brush made contact and appeared to 'soak in'. I'd never seen this before so I tested different areas of the miniature and got the same effect consistently.

    The undercoat was applied very lightly, in short bursts so that it just covered the figure so there was no undercoat saturation. It was also exactly the same can I'd used a week earlier with no problems to report.

    I was just wondering if anyone else has ever seen this, and whether there might be some cause I'm not thinking of. It's a pain to have to go and strip a figure when you're on limited time and had spent a long hard day in the office looking forward to a bit of 'me time'.

    Many thanks in advance.

  2. #2

    Default

    I'm certainly no great or above-average mind, but I have indeed have this problem. Since my oldest army is base colored Blazing Orange, I, too, often spray white. I really have no idea what causes this problem, but I theorize that dust in the air adheres to the mini and makes a granular surface. I find that you can avoid any potential blotting problems by applying a first undercoat of unthinned white paint, to fill in the rough-ish surface. Bleh, I know it's the sledgehammer approach, but I said first thing that I'm not a great mind, right? Hope this helps.

  3. #3

    Default I know what causes this

    I have had this problem in the past and I have learnt the very hard way. I am a professional painter and this has happened to me several times over the years and till recently I did not know why. It is however very simple. It sometimes happens when using purity seal as well when varnishing your model. This is very bad as the spray comes out a dusty white and it runins the finish completely. i actually had this happen when undercoating a £180 commission recently. It was runined after three days work! The problem is simple...yoiu are not shaking the can hard enough. Really shake the can fro about 30 seconds and I guarantee it will not happen. It will happen mre frequently with older tins of spray. but a vigourous shake will stop this.

  4. #4

    Default

    Hey,

    I have had this problem recently as well. I think there are a few things that could solve this.

    1) As you spray in short bursts(like myself) you should make sure to at the end of the spray, flick the can away. This way the spray does not END on the mini. Also starting the spray away from the mini and ending away is good practice.

    ex. Something like this. Start of spray mini end of spray
    >>>>>>>>>> (()) <<<<<<<<<<

    You are essentially just passing the spray over the mini. But in short little bursts. Takes a little practice but reduces the chances of the primer being to thick and leaving a wierd residue.

    2) Make sure your primer is WELL SHAKEN! Spend around 3-5 minutes on this. IT DOES HELP.

    3) Also make sure to test the primer before spraying the mini. Spray a couple bursts on a piece of cardboard or something else to make sure the spray is coming out efficiently.

    4) Make sure you wash your hands before touching the mini, oil from your hands could cause this. Also just.. not touching the mini helps

    5) Make sure you wait a good amount of time before painting the mini after priming. Technically around 20-30 minutes after spraying you could paint. However an extended period of 24(or overnight) Does the trick.

    6) Applying more paint to the area seems to resolve this problem. I use about a 3:1 water to paint ratio for basecoats. (takes a few layers but is worth it) Make sure you wipe your brush off, and it just seems that the area needs to be saturated first(by this i mean water needs to be introduced to the primer surface and soak in before paint can be applied)

    7) Make sure you have prepped your mini properly. Wash it in soap, clean it off, If its metal polish it, and wash in soap again. No oils should be on the mini including oils from your hand!

    Hope this helps, Gary.

  5. #5

    Default

    I've had this problem myself, not with the white spray though but with black.
    It has only started doing it recently so I have a feeling they may have changed the frmula of the spray.

    -T-

  6. #6

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    Thanks for the replies

    The 'dust' idea intrigues me. Normally I spray my figures outside. I mount the figure on it's pin and then embed this in some bluetac on an old shoe box lid so I'm not touching the figure at any point. However, the other night it was hoofing it down with rain and blowing a gale of almost biblical proportions, so I sprayed the figure inside. I'm wondering if that might have exposed the spray to more 'static' air and allowed it to accumulate some dust. Something I'd never previously considered.

    Some food for thought here though, thanks all

  7. #7

    Default

    I had this last weekend but with black spray. I put it down to the fact that the weather in the UK is currently damp and windy and the undercoat dried slightly differently. Thankfully mine didn't cause me too much hassle as I have been mainly basecoating with GW foundation paints.

  8. #8

    Default

    Not to sound sarcastic but the solution to this problem has not been mentioned.
    Stop using overpriced GW spray product, plain and simple. There are other cheaper and a whole lot better primers out there. Do a forum search on primer because this topic has been discussed atlength atleast twice in the last month. Here is one I just found
    http://www.coolminiornot.com/forums/...ad.php?t=35550
    My solution if you want white, use Tamiya Primer, comes in white ( fine and super fine ) and gray. I've used the gray for the last 20 years with no problems. I even sprayed it in a pinch outside at -10 degree C and was just fine. I've never ever seen Tamiya fuzz like other primers.
    My 2 cents......
    Last edited by DXM; 11-25-2009 at 10:37 AM.

  9. #9
    Coffin Dodger / Keymaster airhead's Avatar
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    1. the problem is not dust. It may be humidity. It is most likely insufficient mixing (shaking) of the paint and/or poor technique. The paint is 'blotching' because the surface is slicker than it should be. You have not stirred the flattening agent well into the paint, used it all up previously or are shooting right at the mini (like obsidianpainting showed you).

    2. Second problem. GW undercoats are not primers. They are water based paints - basically the same stuff in the little pots.

    3. Third problem. GW spray paints (colors and clears) have had so many quality control issues over the ages that I am amazed that anyone that has been in this hobby any length of time would use them at all. Combine that with the prices they are charging and I am amazed they can sell a can at all. Now, I'm all for supporting my local hobby shop, but I can buy a case of good primer (6 cans) for the price of one of GW's.
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  10. #10

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    Advice regarding GW primer (that isn't really primer) taken on board and duly noted.

    It certainly isn't technique (I use exactly the technique obsidian mentioned), it certainly isn't lack of shaking (I find it quite therapeutic!).

    So, it seems we're left with humidity (perfectly feasible given the conditions) or the standard of GW paint. Don't ask me why I've never tried a different primer, now it's pointed out to me the threads become apparent. Primer is just one of those things I never really thought much about, and yes I do understand just how bad that statement is.

    I shall have something of a read and change my primer brand.

  11. #11

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    Quote Originally Posted by airhead View Post
    The paint is 'blotching' because the surface is slicker than it should be.
    I think it's the reverse: it's more open or porous on a microscopic level. If the surface were slicker it would be shinier and the paint would tend to bead up, not soak in, no?


    Quote Originally Posted by Devilry View Post
    ...it certainly isn't lack of shaking (I find it quite therapeutic!).
    Ah, interesting. I thought that was the likely culprit.

    Einion

  12. #12

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    Correct me if I'm wrong now, but I don't think the GW primers over here in Europe are the same as those over in the U.S. and Canada. These over here I've personally had no issues with whatsoever, in fact I still use Chaos black as a black "primer" but prefer Tamiya when it comes to white. The Tamiyas are far more pricier then GW's though. The old GW black primer was however superior to the new one IIRC.

    Swedish online prices I found just now:

    Games workshop Skull white: 109kr for 400ml
    Vallejo White Primer: 139kr for 400ml
    Army Painter Matt White: 79kr for 400ml
    Tamiya Fine Surface Primer: 95kr for 180ml = approximately 211kr for 400ml

  13. #13
    Coffin Dodger / Keymaster airhead's Avatar
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    Quote Originally Posted by Einion View Post
    I think it's the reverse: it's more open or porous on a microscopic level. If the surface were slicker it would be shinier and the paint would tend to bead up, not soak in, no?
    You're right. I first read it as it was beading up, not spreading out.

    more flattening agent than in the last batch
    or
    painting from too far away and the paint is partially drying on the way to the mini, giving it more texture
    or
    humidity changes causing the paint to dry quicker (in the air) than it had before - also resulting in more texture.
    or
    spraying too light a coat - waving across too fast - resulting in a very light coat that is rough.

    We are talking rough here on a near microscopic level. to the eyes, it would appear flatter/less glossy.
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  14. #14

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    Quote Originally Posted by Avelorn View Post
    Games workshop Skull white: 109kr for 400ml
    Vallejo White Primer: 139kr for 400ml
    Army Painter Matt White: 79kr for 400ml
    Tamiya Fine Surface Primer: 95kr for 180ml = approximately 211kr for 400ml
    Hycote, grey: 46kr!

    Einion

  15. #15

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    Hycote? Never seen it in Sweden. I know some use car primers though, haven't really made a side by side comparison.

  16. #16

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    I'm sure they must sell something similar everywhere, given the need.

    There's a very high likelihood that car primers of this type will be cheaper than anything made/packaged for the hobby, while being just as good or better.

    Einion

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