BITUMEN.
Someday, after another 100,500 tests and experiments, I'll write an article about bitumen... but for now, I'll share some exclusive information with my blog readers that you're unlikely to hear in full from anyone else.
Many people know that I want to make the second Alert building in a museum style... something like this museum piece:
...based on the principle that Dmitry Shevelev does, here is his model (below):
Not everyone might like this style, and that's understandable; tastes differ, but I really like it!
A quick introduction.
What is bitumen? It's a pigment (essentially oil) diluted in a solvent.
So,
what you need to know about bitumen:
1. If you do everything correctly before applying the bitumen (prepare the surface properly), the result is almost completely reversible within a short time. This is precisely what scares many people about using bitumen. The idea is that you can make the model very black or stained, and it won't look aged, but dirty. Well, if the surface is properly prepared, applying solvent with a brush to a fresh layer of bitumen can almost completely remove it. But after a day, this will no longer be possible.
2. Bitumen VERY clearly shows all defects, scratches, chips, and dents! Therefore, if the surface isn't perfectly prepared, it's best not to use bitumen, otherwise everything will be 100 times more visible!
3. Bitumen CANNOT be applied to bare wood. Bitumen should be applied one month after oiling. Sometimes it takes two months, sometimes two weeks... It all depends on the desired result, but if this is your first time, no sooner than one or two months!
4. The rougher the surface (sandpaper below 200 grit), the stronger the effect will be. And the smoother and more polished the surface (320 grit + steel wool 00 grit and higher), the lesser the effect will be.
5. The deeper the oil penetrates (brush application and long exposure), the thicker the film (which smooths the surface) and the lesser the effect. However, if the oil is applied with a cloth (especially if semi-dry) and wiped dry as quickly as possible, the effect is much stronger.
6. The effect also depends on the oil. Linseed and tung oil penetrate very deeply even in a short time, so the effect may be lesser. But with Danish and Teak (which don't penetrate deeply and dry quickly), the effect will be more visible.
7. By "effect," we mean the wood grain. If the grain isn't filled or smoothed, the pigment will be retained and will be more visible. If the pigment has nothing to adhere to, less of it will remain on the surface. We're talking about wood species similar to pear. On light-colored, soft, and highly porous woods, bitumen may behave differently.
8. But we haven't yet discussed the length of time the bitumen remains on the surface before the excess is removed. The same applies here: the longer the bitumen remains on the surface, the darker it will be... and vice versa. Even if the bitumen has nothing to adhere to (the surface is smooth), if the bitumen remains on the surface for a long time, it will darken... not because the wood grain is filled, but because the varnish acts like a varnish. That is, very small particles will remain on the surface if the solvent doesn't mechanically lift them off the surface during rubbing or if it evaporates.
9. If the surface is large and it's impossible to apply the bitumen all at once, spots or transition lines may appear. But this isn't a problem. If you take a brush with solvent and rub the transitions or spots, the surface will smooth out evenly, becoming uniform in color.
10. I use Idea Patina 710 Patinatura Bitume - Bitumen Patina. I dilute it with odorless solvent for oil-based paints. The resulting odor is generally tolerable (though it should still be used in a ventilated area). Other bitumens are very smelly, downright strong. After applying the solvent, shiny spots sometimes appear on wood (especially on very smooth surfaces). Remember to wipe them off periodically until they disappear completely.
11. Proportions. There's no exact ratio. I added about 1 cubic cm of bitumen to 80 ml of solvent, but most of it still didn't dissolve. Since this bitumen is very viscous, it needs to be dissolved in small portions in a small amount of solvent, constantly rubbing the clumps with a brush. And before use, don't shake it; stir it gently, while drawing a circle with the bottom of the bottle on the table.
12.
Technique. How I do it.
First, I dip a medium-sized brush into the solution (stir it first, but don't shake it) and squeeze out most of the solvent on the sides of the bottle to prevent drips. Then I apply the bitumen to the surface and rub it in, filling corners, joints, and crevices. Another important factor is the time the bitumen sits on the surface before removing it. This needs to be tested on samples. As stated earlier, all these factors affect the time. But first, it's best to apply a thin, non-dark layer for a short period of time, then add more if needed. You should also monitor the surface, not letting certain areas dry too quickly to avoid blotchiness.
Then, use a second, dry brush to wipe off excess bitumen, constantly wiping the brush on a napkin (so it stays dry and absorbs the bitumen). Essentially, apply the bitumen with one brush and wipe off the excess with the other. Experience will tell you when to wipe off the excess with a napkin. Doing this immediately will remove the entire effect. If the bitumen remains on the surface for a long time, you won't be able to remove it. But remember, if you feel the effect is excessive, apply solvent with a brush, rub it in, and then wipe off almost all the bitumen with a napkin. Repeat the process if you've removed almost all of it.
I apply bitumen first to the main surface (for example, the deck) and then separately to the other elements (gratings, bits, etc.). Then I secure the parts to the deck. Then, I add bitumen to the joints between the parts and the deck with a fine brush (this also applies to the hull if it's on the outside of the model). I leave a little extra bitumen in the joints and evenly blend the rest into the surrounding tone. This creates the effect of enhancing the dark tones in the corners. It also gives me more control when doing everything separately first. You can also pre-tint the areas on the deck under the guns a little more to naturally accentuate the darkness underneath.
13.
I recommend coating samples, and especially the finished product, testing it in different lighting conditions. Because under artificial light, it may look different, but under daylight, it may appear different. Under strong direct light, the surface may appear lighter, but in low light, it can be very dark. After coating, it's essential to check everything and, if necessary, remove any excess. Otherwise, there's no other way to do it without mechanical treatment.
14. And finally, there are two options. Option 1 is a more pronounced texture and a darker look. Option 2 is a light tint... and everyone chooses what they prefer.
Below, I'll show
my results for option 1. Since the lower deck will be practically invisible, I decided to go for a more intense museum-style tint to see if it would suit me or just a light tint. The surface was polished with 320 grit and 000 grit steel wool. However, the wool couldn't penetrate the corners well, so they're not as smooth as the center, and that's important! Plus, I applied the oils not with a brush, but with a semi-dry cloth, which also didn't penetrate the corners well, resulting in less oil in the corners... and that's also important; you'll understand why later. In the corner of the photographs it will be indicated that a certain oil (Tung or Danish) was applied before the bitumen.
The photos above and below clearly show that the oil not only affects the overall color of the wood, but also that, even with the same wood treatment and oil application method, Bitumen adheres less well to Tung Oil than to Danish Oil. Danish Oil has a more pronounced texture.
And in the photo below you can see that if the part was poorly polished, all the flaws will appear on it.
By the way, the bitumen has caused the black plastic hinges, which are coated with paint, to have a slight sheen, and this sheen is very similar to metal. This needs to be verified on the rims.
It's important to keep in mind that the entire lower deck is assembled from scrap material, especially the walls... Also, unfortunately, photographs can't accurately convey the color, shade, or degree of darkness. Some have black surfaces, others are lighter, or brown or gray. Therefore, I'll show different ones to give a general impression. And the hull has a different shade...
So, in essence, the colors and shades in the three groups of photographs are completely different... from reddish-beige to gray to reddish-brown... But the most annoying thing is that none of these colors convey the original shade, which is a shame. Although there are some similar tones in the first and last photos, it is difficult to say for sure, but the gray and very bright brown ones are definitely not the same.
What do you think?