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Grainy acrylics?


Eugene

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Hi folks,

 

I've only just come back to scale modelling after a 25 year gap, so taking it slowly!

 

I've started out with a 1:72 Spitfire and I'm finding that my paint in some areas/colours is really grainy - I'm using Humbrol Acrylics and brushes (I never graduated to an airbrush!)

 

Is this 'grainy texture' due to not mixing the paint enough, not thinning enough, or just duff paint?

 

Any ideas or tips greatly appreciated!

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I could be accused of bias, but even when airbrushed most water based acrylics will dry with a rough texture. Some worse than others.

 

Bad surface finishes normally involve either coarsely ground pigments, drying too fast, or both.

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Humbrol are known for grainy texture. Not the enamels, just the acrylics. Ever since they 'upgraded' to a pot with a red wave on it, the paint has been this consistency on many pots. I won't be buying any more of it unless it is proven to have been changed and all such pots removed from sale. Take a brush out sample back to where you bought it and let them see, as no other paint I have come across has this problem to that extent.

 

This is also the reason many say they cannot airbrush it; the 'grit' in the pots. I believe it may be some form of matting agent, as the grit is not present in their gloss paints, and much less prolific in their satin paint (but still there to a certain extent)

 

You might want to shoot an email off to Humbrol as well. The amount of time this has been going on in their acrylic paint, I wonder whether they want to drive themselves out of business.

Edited by sapperastro
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Ah, ok, interesting

 

strangley, I bought a Humbrol hobby tray which included a free Spitfire ‘starter’ kit with paint - the 29/brown paint it includes seems WAY better and no grain/gritbissue at all

 

could it be the age of the paint causes the grain/grit to form?

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It isn't the age, as some of my older variants of HA are perfectly fine. It seems to be screw top pots with the red wave that goes down in the centre and then up. See if all the pots look the same, and then check the batch numbers.

 

If it is the little 3ml clear pots of paint, there is no way of knowing, but you can be certain that the batches would come from different times (or different factories?).

Edited by sapperastro
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Hi Eugene,

 

I've had this issue with Hu29 and Hu30 acrylics. I have managed to improve my finish with these paints by knocking back the graininess with micro mesh. I got a pack of 6, grades 800-3600 off of amazon for about £10 I think. 

 

The way I have used it is by gently rubbing a high grade over each dried coat of Hu29 in a small circular motion. Just be careful around raised surface detail. It was also great for sanding down filler to a smooth surface. 

 

This is by no means "the way to do it". I'm a very inexperienced modeller coming back to the hobby over the last 3 months and just found this helped me overcome this issue somewhat on my 1:72 Hurricane. More experienced guys may have another tip.

 

I said previously I also had this issue with Hu30. Going off topic a bit, I was finding it not only grainy but very.. erm ..green. After reading other threads on this forum I decided to get the hu116 acrylic and this paint behaved much better than hu30 and looked more like RAF Dark green on my 1:72 Tiffy. 

 

 

 

Edited by NoGoodBoyo
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Eugene if you want a good brushing Acrylic then I would go for Vallejo.

Vallejo model is their brushing acrylic. Bu depending on what you are doing it does need,

thinning.

 

Vallejo Model Air although produced for airbrushing I have found good for brushing as well

but you will need more coats of paint.

 

I understand what Jamie has said about the grainyness of acrylics. But would not say that

it is rough at least not Vallejo. If you want it smooth smooth then a coat of Vallejo Acrylic

Varnish will do that.

 

If you do use Vallejo then use their thinners, not water. The thinners contains all the ingredients

that the paint holds. Water has a property surface tension and is not a good laying flattening out liquid.

Edited by LaurieS
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All Vallejo brushes well, as does Hataka and both leave a good finish. I lean towards Hataka as the colours seem more accurate, though Vallejo may have raised their game in that area recently.

 

Having said that, some Humbrol paint goes on well straight from the pot, Hu90 especially. If it doesn't, add flow improver and retarder. Water works fine for thinner but better results may be achieved with Isopropyl Alcohol (IPA). If the surface is a little rough, rub down with a fancy product such as micromesh or use the poor person's solution, a piece cut from a pair of tights. Really, it's all a bit 'hit and miss' with Humbrol, quality control hasn't been consistent over the years and you can't be sure what you're getting. One tip, though: don't buy it in flip-top pots.

 

I'm still experimenting and far from an expert, but look up posts from Britmodellers such as @robvulcan for top advice on acrylics and brush painting.

John.

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1 hour ago, LaurieS said:

If you do use Vallejo then use their thinners, not water. The thinners contains all the ingredients

that the paint holds. Water has a property surface tension and is not a good laying flattening out liquid.

2

Just should have added that the Vallejo Thinners gives the paint flattening out and also adhesion properties which

are inherent in the undiluted paint ie using the Vallejo thinners you are not diluting its properties.

 

Also to add Vallejo Primers are yucks. Use Stnylerez 300% superior.

 

Laurie

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Thanks everyone - I've bought a couple of Tamiya acrylics to replace the 'grainy' Humbrol ones - it does seem a bit hit and miss with my Humbrols.

 

The Tamiya's seem fine, but then so does the 'free' pot that came with the Spit.

 

I'll just have to do tests with any new pots I guess!

 

 

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Tamiya can be a pain for brush painting. Thinned first coat is fine. It is the coats after that you have to watch out for, they can lift the first coats right up if you are not careful. An acrylic retarder and possibly some of their acrylic thinner may be needed.

 

If you can get them, Vallejo, revell Aqua both quite good with brushes once thinned a little.

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17 minutes ago, sapperastro said:

Tamiya can be a pain for brush painting. Thinned first coat is fine. It is the coats after that you have to watch out for, they can lift the first coats right up if you are not careful. An acrylic retarder and possibly some of their acrylic thinner may be needed.

 

If you can get them, Vallejo, revell Aqua both quite good with brushes once thinned a little.

Agree Tamiya, a fine thin paint, is difficult to hand brush. For airbrushing I add 25% thinners to 100% paint.

With that thinness, I have had some success hand brushing but only in small areas. Problem is that it

is a very fast drying paint beautiful for airbrushing.

 

Laurie

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  • 2 weeks later...

I have recently finished a Sword Vultee Vanguard and used Humbrol 29 out of a screw top jar that I bought fresh and it seemed OK to me. I airbrushed it with Windsor and Newton flow improver as de-ionised water as thinning agents. It dries to a very matt finish, but not what I would call grainy, but I have come across the problem with some of their other matt paints.  Personally not a fan of Humbrol paints, they tend to give inconsistent results and some of their colour matches are a little dubious. I use a mix of ranges depending on what I need. I am lucky in that I have access to about seven paint ranges in the shops I can get to. 

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1 hour ago, Martin T said:

I have recently finished a Sword Vultee Vanguard and used Humbrol 29 out of a screw top jar that I bought fresh and it seemed OK to me. I airbrushed it with Windsor and Newton flow improver as de-ionised water as thinning agents. It dries to a very matt finish, but not what I would call grainy, but I have come across the problem with some of their other matt paints.  Personally not a fan of Humbrol paints, they tend to give inconsistent results and some of their colour matches are a little dubious. I use a mix of ranges depending on what I need. I am lucky in that I have access to about seven paint ranges in the shops I can get to. 

Windsor and Newton Improver is to break down the surface tension in water in artists acrylics and water added to them to thin. Artists acrylics are different to Model Makers acrylics the artist type usually hand brushed.

 

Vallejo Flow Improver, for instance, is to stop paint drying on the needle and in the nozzle. Works extremely well. For effects I add 50% with Val. flow improver and with 10PSI. For thinning I always use a paint manufacturers thinners as it has the ingredients in their paint.

 

Laurie

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Oddly enough though I have some trouble with the Vallejo flow improver not doing what it is supposed to do but it may just have been me. I agree for some brands I always use their thinners as they work well, but I have found Xtracyrlix thinners did not did not the stop the paint clogging the airbrush when flow improver and water works well. Might just be rubbish technique on my part. 

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I'm no expert, but I try very hard. All my modelling is on the dining room table, so enamels and and airbrush are a non-starter for me.

 

I'm moving away from Humbrol acrylic paints, I find them to be not the best for brush-painting, not necessarily because it is hard to avoid brush marks, just because of the grittiness. I find the little pots that come with the starter kits more grainy than the regular stuff, but with both I find that even when thinned a lot and stirred excessively I still get little gritty lumps in the paint that have to be polished out, which is a nuisance.

 

I haven't settled on my brand of choice to replace my Humbrol though- the jury is out between Revell Aqua and Xtracrylics. I find Vallejo model a bit thick for brush painting larger areas, difficult to avoid brush strokes even when well thinned- it is brilliant for small figures though (I only do 1:72). Tamiya acrylic again I like for figures and small details but I find it dries too quickly for brush painting larger areas, but that might be me.

 

Whatever paint I use it gets a good dollop of W&N Flow Improver as a thinner.

 

 

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