Airbrushing Humbrol Enamel (What am I doing wrong?)

Discussion in 'Painting Questions, Tutorials and Guidebooks' started by waterman, Jan 7, 2013.

  1. waterman

    waterman Member

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    Airbrushed Humbrol Enamel for the first time and screwed up the base coat. The surfaced looks flocked (rough). I put about 4 or 5 drops of paint in my airbrush cup and 2 drops of lacquer thinner. Noticed the atomization of the spray was splattery. Added another drop of lacquer thinner with no improvement. Repeated with another drop, and still the same results. Was wondering if lacquer thinner might not be compatible with Humbrol, or perhaps it's an air-pressure / paint mixture problem. Anyone have any suggestions?

    Also, would like to strip the paint and start over. Anyone know a good paint stripper that will remove the paint with little scrubbing? Would like to avoid scrubbing due to the delicate PE pieces.

    Here's the disaster. Click on the thumbnail photo.

    [​IMG]
     
  2. Airframes

    Airframes Benevolens Magister

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    Bit difficult to see the result properly, as the pic isn't quite sharp - don't know if this is the pic, or due to using an image-hosting system. Normally better, and much quicker for the viewer, to re-size and upload direct to the forum.
    Anyway, Humbrol enamels should be used with an enamel thinners or white spirit (Turps substitute). I think there would be a reaction with the thinner you're using, causing separation of the pigment. however, from what i can see in the photo, it looks as if the paint is rather heavy (possibly due to the pigment separation, possibly under thinned), and has been sprayed at either too high a pressure, or too close, or a combination of both.
    Since the demise of Humbrol as a company, and the closure of the factory, wherever the paint is made now, it can be of dubious quality and lacks consistent quality. This has caused me some problems over the last couple of years, and I've sworn by, and been using Humbrol, for fifty years!
    Depending on the colour, I normally thin at around 60/40, that is 60% thinner, but can often get away with 50/50, using enamel thinners or white spirit. This should be prepared, and thoroughly stirred in, in a separate container, and then decanted into the airbrush cup. It's not possible to mix adequately in the airbrush cup, and the paint must be thoroughly stirred before use, especially matt paints.
    My compressor does not have a pressure adjustment or pressure gauge, and normally works at around 15 psi, and I only use Humbrol enamels, which work fine - when the paint itself is ok.
     
  3. Wurger

    Wurger Siggy Master
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    Undoubtedly the thinning process wasn't carried out properly. The mix ratio should have been 50/50% or 50/60% where the second number is for the thinner 50 or 60%. What kind of the lacquer thinner did you use?
     
  4. waterman

    waterman Member

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    :p
    I apologize for the poor viewing. Pure laziness on my part. I know my photos are too large for this forum and don't have any photo shop program. Would have to visit one of those free websites to re-size. What is the forum's size restriction for photos?

    Was thinking it could be the lacquer thinner, but then noticed my control panel came out OK. I tried varying the air pressure, probably 8 psi to 25 psi, using a gravity feed AB...still didn't matter. Now I'm thinking it probably was a mixture problem...like you said, mixing in an airbrush cup does not insure good mixture. It might explain why it seemed to spray ok for a few short bursts. Or perhaps it might also be a moisture issue (raining and my moisture trap leaks air).

    Do you mind sharing what type of problems you experienced? Did you experience what just happened here, or was it a color matching issue, or bad paint? I had one tin that seemed bad...stirred and stirred, but just couldn't get the paint mixed (the pigment part of the paint was just too hard).

    Thanks, that's great advice. Next time I'll remember not to mix Humbrol inside my airbrush cup. That seems like it could very well have been the issue.
     
  5. waterman

    waterman Member

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    I used Klean Strip Lacquer Thinner. It seems to work with Model Master enamels.
     
  6. Wurger

    Wurger Siggy Master
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    I see... I use the Wamod thinner or the Humbrol one.

    [​IMG]

    And any Photoshop program isn't needed for re-sizing pictures. Just download and instal the Irfanview image browser. With the program you can do that in an easy way. ALso the program can more. We recommend the width of a picture of 800 pixels.
     
  7. Crimea_River

    Crimea_River Well-Known Member

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    I've used lacquer thinner with Model Master enamels for years without a problem. As a thinner, it's quite "hot" (i.e strong) so more care needs to be exercised than if one used the recommended thinner. It looks like you started with a 50% ratio and ended up with almost 75% thinner. If the problem originate on the first coat, the thinner coats would have been unlikely to fix the issue.

    Assuming the paint was OK, I can only suggest by the looks of your picture that your first coat might have partially dried in the air before hitting the model. High pressure or too much distance from the surface could cause this. If you can run your finger on the surface and remove some dust, that would be the issue. If not, it's possible there was not enough thinner and the paint was clumping, or as the boys above suggest, there was a reaction with the paint.

    As for removal, I've never tried this but I've heard that soaking the parts in brake fluid will remove the paint. For the metal parts, I have no doubt that your lacquer thinner will remove the paint but, for heavens sake, don't do this on the plastic as it will also dissolve the plastic - it's that strong. I use this stuff to clean dried paint from my metal airbrush parts and it works great but I never want to get it on plastic.

    Good Luck!
     
  8. waterman

    waterman Member

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    I actually have a tin of Humbrol thinner. I probably should have used it, but since it's pricey, I told myself I should save it for brush work. Wamod is a new to me...haven't heard of it before. Pretty sure we don't have that here (Hawaii). I think the island has only 3 small shops that sell a small selection of model paints. Tamiya and Model Master seem to be the popular brands, but the selection is still quite limited. I wish more internet stores would ship paints to Hawaii, but it seems most rather not bother with the hassle.

    Wow, thanks! I tried it out and it seems simple enough. Guess I'll be able to post photos directly now. I'll have to give it a try.
     
  9. waterman

    waterman Member

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    The first coat was definitely bad. It splattered, but the paint looked pretty wet. I thought perhaps the air-pressure might have been too low, so I increased it slightly and just started spraying. When it still splattered, I decided to thin it more. But then I thought the paint in the cup was getting too watery. Then I gave it a quick huge blast. Lots of paint shot out and flooded the paper (too wet). I decreased the air-pressure a bit and it was spraying ok for a little while. I'm thinking Airframes made a good point about not trying to mix the paint directly in my airbrush cup. The paint was probably not mixed very well.

    A
    Thanks! Brake fluid seems like the best suggestion so far. I know someone who used it to strip chrome parts and it seemed to work fine (didn't damage the plastic). Others have recommended oven cleaner or Easy Off, but it doesn't sound like I would be able to soak my parts using Easy Off. I imagine I would have to do some scrubbing, but that would probably damage the photo etch.
     
  10. Crimea_River

    Crimea_River Well-Known Member

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    Yeah, mixing in the cup is not a good plan, especially with a gravity feed brush.
     
  11. stona

    stona Well-Known Member

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    I'll second every word that Airframes wrote about Humbrol. I've been using their enamels for a long time too (not quite 50 years but I'm closing in!)
    I have always thinned with good old white spirits (mineral spirits in the US),either from a local hardware store or,nowadays,from one of the big DIY chains. It's very cheap compared with branded thinners and has always worked well.

    Quality issues? Two examples. I opened a tin of matt black recently and the content was like tar,horrible. I also bought "Aluminium" (56) recently and the content is just not metallic but an awful grey colour. I've chucked them both.

    Cheers
    Steve
     
  12. Airframes

    Airframes Benevolens Magister

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    Steve has described two of the major problems with current Humbrol paints. Others include:- very thin and watery, the opposite, very thick and rubbery. Also, refusal to dry fully, remaining 'sticky' and semi-gloss (with matt paints) for up to a week. Colour problems include totally different shades to what is shown on the tin lid, with sometimes different shades from two of the same colour. Also, metallics being quite poor, with Number 11 'Silver' being a good example; this used to be a bright, shiny, almost chrome silver, and is now a 'speckled' dull silver, rather like a metal flake car finish.
    I also find that the problems are more prevalent in certain colours, greens in particular, and many 'go off' in the tin within a very short period. I have some original Humbrol which is 30 years old, and is still fine, but a tin of matt white, purchased in early November, and opened twice, has now gone thick and almost solid.
    Humbrol were once the best modelling paints in the world, bar none, and their old (now discontinued) 'Authentic Colour' range were spot on and superb. the only reason I continue to use them, for now, is the lack of alternatives locally, but I will be changing, probably to Model Master and Xrracolour, once my stocks run down sufficiently.
    I wrote to Hornby Hobbies (who own the brand name) some time ago, but have not received a reply.
     
  13. stona

    stona Well-Known Member

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    I think Humbrol paints are manufactured in the mythical land called "The Far East",possibly China.They've certainly taken a dive in quality.

    I am now using mostly old tinlets for detail painting,interiors and the like. They should last a long time,there's only so many red levers and yellow knobs in most cockpits :).

    For camouflage and exteriors I now use White Ensign Colourcoats and do not replace the Humbrol paints as they run out. The Colourcoats are very nice high quality enamels not unlike the old "authentic" range mentioned above and I would recommend them to any enamel user. I order them direct from White Ensign's website.

    It's a shame,Humbrol is a brand that I've used since I was about 10 years old (and that is not the day before yesterday) but I can see a time when I won't use it at all.

    Cheers

    Steve
     
  14. Crimea_River

    Crimea_River Well-Known Member

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    The only way they'll listen is to stop buying them. Humbrol was my paint of choice back in the 70's and I still have some of those tins which are still good, and probably better than their new stuff.
     
  15. stona

    stona Well-Known Member

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    Likewise. I still have some tinlets that are,if not 70s vintage,at least 20+ years old and they work fine.

    Cheers

    Steve
     
  16. waterman

    waterman Member

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    Wow, thanks for the heads up! That explains why my one tin was super rubbery and would not mix. I figured it was just an old can that sat on the store shelf for too long. Wish I had known earlier (just spent another $50 on more Humbrol).
     
  17. Airframes

    Airframes Benevolens Magister

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    Thanks for the reminder about WEM paints Steve, I forgot about them.
    Maybe I'll re-stock with a mix of WEM, and Xtracolour for some colours - both have to be ordered on-line/mail order, so no hardship with either. Unless Hornby find a better manufacturer for Humbrol paints, I think I'll only be using them in the future for small detail jobs with basic colours, if I need to buy in 'a rush', locally.
     
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