September 4, 2010

Preparing for Painting on Hardboard (Masonite)

Hardboard, often incorrectly referred to as Masonite®, is a relatively stable substrate for oil and acrylic paintings. Formed of wood fibres in a technique similar to paper production, it does need to be properly prepared to avoid degradation of both the substrate and finished painting.

Typical hardboard is dense, tends to be dimensionally stable, and is relatively cheap. It is formed of coarse wood fibres pressured together to form a sheet, similar to paper. The Masonite® process was used by a US manufacturer to produce its particular brand of hardboard last century, and is incorrectly used to refer to all hardboard.

Most modern hardboards are prepared by similar processes and can be used. Avoid oil-tempered boards (unless you are prepared to use oil-based sealers), at least partly because one cannot always be sure what type of oil has been used.

Hardboard is easily cut, though if you do not wish to buy pre-cut and pre-sized panel from your art supplier (or if you require a custom size) consider going to a kitchen or furniture jointer/manufacturer directly and ask them to prepare panels for you. If they are able to use off-cuts then you might get a bargain. Alternatively you might need to buy a whole sheet (typically 8’x 4’ or 2400 x 1200mm) worth of panels. Sit down in advance and work out how to minimize wastage. Get together with another artist if need be and share the sheet between yourselves. Also be aware that some building suppliers also supply half and quarter sheets, and may even cut them for you.

Also consider the thickness of the panel. I typically use 4.75mm ( 3/16”) thick panels for panels up to 18”x 24”. Above that you may need a support frame, a thicker panel, or even two panels glued together face to face (keep one good face outward for painting on) with a construction adhesive.

Sealing and priming is important as hardboard has a large percentage of tannins (that’s why it is dark brown) which can migrate out of the board over time and stain paintings (SID or Support Induced Discolouring). This might take decades (depending on the environment the painting is hung in), but can ruin a good painting. Hence, there are three main steps I recommend:

i) Sealing

ii) priming

iii) final priming for media used

The sealing keeps the tannins in, and also protects the board. Personally I like a product intended as a sealer, though many gessoes claim to be sealers and primers. In such a case apply at least three coats by roller, brush, or spray. Make sure the coats are even.

For me, I follow the following sequence

Sealing:

I tend to use Chroma brand Binder Sealer, which is sometimes sold under the Atelier® or Jo Sonja® brands of the company. As hardboard is very absorbent, I tend to dilute the first coat with around 10-20% water and almost flood it on by a tapered filament synthetic house brush, or a mottler (brush). A second coat is applied, once the first coat has dried, undiluted. Care is taken to ensure an even coat free of brush strokes.

Priming:

For this I use two to three coats of an acrylic gesso. Often I like to create a fine texture on the board, resembling fine canvas. Hence I use a high-build acrylic gesso like that produced by Pebeo® or Matisse® (Derivan Ltd). A first coat is applied by the abovementioned house brush and laid off to ensure fine brush lines remain in a vertical or horizontal direction. In the next coat, the gesso is applied and laid off with the brush to leave fine lines at right angles to the first coat.

Final Priming:

Here I apply a further sealing/priming coat of Golden® GAC 100, avoiding brush marks. When dry I apply a further priming coat of either Golden® acrylic gesso or Schminke® gesso

Coloured Ground:

I tend to apply these thinly and wipe them on by rag. Typically I use an acrylic paint mixed with either Matisse® or Golden® transparent gessoes, or with the Schminke half-chalk primer.

Ideally the panels are stored vertically, not touching each other (perhaps a small offcut of card separating them at the top), until ready for use.

Because of the process involved, it is best to do a number at once, perhaps inviting some artist friends around and creating a production line.

Pure Resolve - What Resolution for Printing Images?

If you are going to print an image, what resolution do you need? Do you need a professional 15MP camera? Can you get away with a lower resolution camera? What are all these terms?

So what resolution do you need? In many ways this is the 64 thousand dollar question. The real answer is, whatever you can get away with.

Ideally you want to use a starting image with the highest resolution you can manage. It is the resolution of the original image which is most important – not the resolution of your printer. Remember also that if cropping a digital image, the resolution, or number of pixels (dots) is going to be less than in the starting image. Hence trying to print a closeup of Uncle Fred in the back row of an extended family group shot is not going to be the same as if the photographer had taken an individual photo of Uncle Fred.

Given the world is not always ideal, we have to work with what we can. So then, what should you aim for, and what can we get away with?

A general rule of thumb for a very good high quality print is 300dpi (dots per inch), sometimes known as 300 pixels per inch. This is calculated from the size of the printed image, not the original. Hence for a 5”x 8” printed image you would aim for 1500 pixels x 2400 pixels. For a larger 10” x 16” print of the same image, ideally you want a starting image of 3000 pixels x 4800 pixels. For an image off a computer scanner, this later figure is readily achievable but, if using a camera image, we are talking about cameras with a resolution of around 14MP (megapixels), which you will currently only find on very high end professional cameras. Obviously, if you have an 8MP camera (quite common), you are not going to meet the 300dpi optimum.

What do we then do? In most cases the 300dpi image is something to aim for, but rarely achieved. If you are printing ultrasharp images, requiring razor sharp resolution (imagine you are taking a photo of a bird where every hair on every feather has to be individually distinguishable) you will want 300dpi or higher. This type of image is the exception, and often you can get away with 200dpi, or even lower.

A deciding issue is the nature of the image. Landscape images can sometimes get away with less – I’ve printed a moody forest scene up to 24”x33” based on an image taken with a 2MP camera, with no problems. For portraits, where sharp detail is required, the naked eye would probably start noticing issues if you used less than a 12MP camera for the same size print. A lot has to do with the human eye – it is more critical of some images than others. The reality is, if you are pushing the limits, then you might either have to compromise or play around a bit and do a few test prints yourself.

What if you have a low resolution starting image – can you just increase the number of pixels in Photoshop? Probably not – as it cannot fix what is not there. Basically – garbage in, garbage out.

However, having said that, there are some compromises which can be reached – e.g. using some of the built-in filters in Photoshop can make a large print from a poor quality original seem more acceptable to the eye. For instance, if I have an image whose composition I love, but is slightly out of focus or blurred – and where I have no other choice – applying the Watercolour filter in Photoshop can often make the image more aesthetically pleasing; essentially where a painterly effect exists, the eye is less critical of imperfections (the brain assumes that the imperfections are part of a deliberate effect).

If you are doing your own printing then do a couple of test images. Very often it is the subject matter of the image itself which will determine what resolution is, or is not, acceptable. Even if using a professional printer, I suggest you buy a cheap inkjet printer (you can get one for less than $80) and do a test print or two before sending off – you will readily identify any immediate problems, rather than having them come back to you (or even worse, just proceed anyway).

What do resolution professional printers require or prefer? Check with them – either on the phone, in person, or on their website. They can give you specific advice, based on their experience, as to what they need and what you can expect based on what you can provide.

A warning to artists regarding art reproductions for sale:

Be aware that original image resolution (which is very different to print resolution – i.e. the resolution of the printer) is only one factor in the quality of a printed image. Anyone considering high quality reproductions of their artwork, to sell, will need to seriously consider professional scanning (or photography by someone set up to photograph artwork), and the need to invest in time by the printer to colour match (and no, you can’t generally take colour matched work from one printer to another and expect it to work – every time you change the brand of ink, printer, type of paper or canvas the image is printed on, it needs to be re-colour matched and calibrated or you will get very different results). Every time I print on a different type of inkjet paper (or other media), or swap printers (I have 5 different printers) I have to go through this process.

As a note, proper colour matching and calibration can sometimes take over an hour’s paid time by an expert (and not all so-called experts have the required extensive training or background). Some firms will perform free colour matching and calibration, on the proviso you do future printing through them (one bonus of that, being consistency in output).

If like many artists, you take care in mixing the right shades and hues of paint (or other media) in your artwork, the last thing you want is for reproductions to look like a cheap painting using a one dollar childrens’ paint set, and then printed on a biscuit tin using 1930s printing technology. If you think that is a joke, I continue to see far too many supposed art reproductions which look just like that. And how different can colours be when you don’t do things properly – I’ve seen reproductions where the colour of light cobalt turquoise has come out the colour of cobalt blue.

Loose canvas! Call the Mounties - Mounting loose canvases

If you have an artwork on loose sheet or canvas, what are your mounting options? Here is another alternative to stretching over a frame, which can be cheaper and more easily achievable for the average artist.

Occasionally I prefer to paint on loose, rather than stretched, canvas – in such cases I tape the canvas to a hard surface, which is quite different to working on a stretched canvas. If you have been following my blogs, you’ll also note that I have been experimenting with inkjet on canvas and other sheet media.

The big problem often arises when you have your finished artwork, and try to decide how to hang it on the wall. Sandwiching it behind mat board in a frame is not always satisfactory, and often the glass detracts from the texture of canvas – accordingly I prefer to leave it off. So how then do you hang a saggy canvas.

While one option is stretching over a wooden frame, it is often not my preferred option – if I wanted a stretched canvas, I would have used one to begin with. Instead I favour mounting the work onto a suitable backing board. After considerable trial and research, there are two methods I prefer.

Method 1 – hardboard (sometimes incorrectly referred to as Masonite)

I prefer hardboard amongst wood products. It doesn’t have adhesives like mdf (medium density fibreboard) uses to hold the particles together, and has been used in the art industry longer than mdf. Wood and timber panels (including plywood) can exhibit dimensional instability over time if not properly sealed and protected. Of these also, hardboard is probably the easiest and cheapest option to obtain.

I seal the front smooth face of a hardboard panel with a suitable sealer. Chroma (through its various brands Jo Sonja, and Atelier) produce a binder-sealer of artist quality. Most other brands do too – for instance I’ve also used Golden GAC-100. It is important to apply a sealer according to instructions (usually 2-3 coats, sometimes diluting the first coat 10-20%) as this prevents tannins migrating from the wood of the hardboard over time. The same applies to the other timber products mentioned above.

At the same time I seal the back face of the canvas with the same sealer, so as to help protect the fibres and increase the longevity of the work.

When the painting/work on the canvas is thoroughly dry, as are all sealers, I bond the canvas to the sealed face of the hardboard panel. For this I use an acid-free book binding adhesive (locally I use a product by Helmar). I use a largish house paint brush and work quickly, pouring the adhesive out of the bottle on to the panel. You could also paint the back of the canvas, but I find it easier to spread on the panel.

Carefully centre the canvas and, starting at the middle, gently lay it out. Do not push down on it yet – you may need to do some small alignment changes to make sure it is square on the panel. Once everything is aligned, start smoothing out from the centre of the canvas to remove any air bubbles. You could lay a sheet of tissue or glassine over the canvas and use the side of your hand. Alternatively you could use a roller or printmaking brayer. Make sure there are no bubbles or ripples, and you will need to work fairly fast.

Next, place the panel on a flat firm surface, lay a sheet of glassine over the top to protect the artwork, then another panel of hardboard etc. Place a few heavyish books or weights on top (making sure they’re not too heavy for the paint on your canvas) and allow to dry overnight.

If you have excess canvas at the edges of the panel, you can carefully trim these off with a sharp knife (suggest the panel is face down on the workbench when you do this), or wrap and glue them (with the same adhesive) around the edges and on to the back on the panel. If following this option, make sure the panel is a good size for the canvas, so you can do this (and ideally so the painted portions wrap around the edges of the panel)

You now have a canvas mounted on a hard panel which can be inserted into a frame sans (without) glass. Whether you use a ready bought, or custom made, frame is up to you. You can also think about other options for hanging the panel.

Method 2

Very much the same as method 1, but I use an acid free heavy card instead of hardboard. In this case I do not seal the card, but still seal the back of the canvas as I believe it helps protect the canvas against degradation.

August 18, 2010

Ground effects - inkjet on canvas

There’s a certain satisfaction, and unpredictability, in coating your own canvas and printing on it. It’s not hard, but does have a bit of a learning curve to get the results you want. However, master this and you have the tools to create something unique and different.

Following my foray into inkjet printing on watercolour paper, I tried printing on gessoed artist’s canvas. Can you print straight on to gesso? Probably not as different gessoes are very different in properties, as are the inks used by different printers. My initial experiment showed that I could print well with my HP A3 printer, but the ink wouldn’t dry properly, and readily rubbed off.

Using the Golden digital ground gave much better results but, as for the watercolour paper, even the best inkjet settings I trialled delivered too much of some colour inks to the surface. The result was that certain colours pooled on the surface with a semi-gloss sheen while other areas were matt.

Despite this, I found you could still get high definition resolution – in one portrait photo I trialled, individual strands of hair, eyelashes, and eyebrow hairs were clearly distinguishable – something I was surprised at given the relatively coarse nature of canvas. [Unfortunately, because I decided to photograph the original late at night (while writing this blog) under artificial lighting at a slow shutter speed, the accompanying image is much less sharp and colour correct than the original canvas print.]

What about the quality of the image (contrast, colour rendition, etc.). Canvas should be treated like any other paper – when you swap between them the results are different. I found, using the digital ground, that colour saturation, contrast etc. were comparable to matt archival inkjet paper I use.

How you finish the surface also affects the final result (particularly the problem of different areas of sheen from the inks). Initial tests quickly showed that if you want to apply water based coatings, it is best to spray them (as they tend to shift some of the ink).

The most foolproof method I found was a couple of initial spray coats (aerosol can) of Nuart gloss or semigloss varnish, followed by at least two coats of Golden satin archival varnish. Personally I found the Golden archival satin varnish gave the best looking finish, and with the added protection of UV protection.

Would I do it again? Yes. It is quite fulfilling, and actually constitutes more than putting some media in the printer and hitting the PRINT button. My advice however is:

try using different grades of artists canvas with different textures;
use a digital ground and apply this evenly (very important);
let the ground dry thoroughly before printing;
do small test prints first on the canvas (with ground applied) as you may need to make significant adjustments to contrast, brightness, colour balance, etc. than if you were painting on inkjet paper;
familiarize yourself with the different characteristics of the coated canvas, and work with them to create something different;
once you’ve master canvas, try other fabrics and textiles (just make sure they’re thin and flexible enough to feed through your printer);
also remember that most inkjets weren’t specifically designed for media other than inkjet paper and that damage is possible. However, as printers often cost less than a replacement set of inks, the risk is often worth it.

August 17, 2010

Getting grounded - digital printing on watercolour paper

Recently I've gone back to my photographic roots and experimented with digital (inkjet) printing my photographs on to different watercolour paper media. It's a pity most watercolour papers contain no technical information, such as whether internally or externally sized or not, something which has a big impact on results.

There's a high learning curve as different printers use different inks which can produce quite different results. Even different colour inks on a printer can behave quite differently (some bleed more, others form a separate coating on top, others just soak in and lose saturation). A problem, perhaps, but also an opportunity to try something different.

I also tried using Golden Digital Ground – a Golden product which makes surfaces more adaptable to inkjet printing. What I discovered is that applying this is like wet watercolour painting – the paper will stretch. Ideally you should stretch and tape your paper to a board (like you were going to stretch watercolour paper prior to painting), but you might be lucky (for some paper types) to just tape the edges of dry paper to a board prior to coating with Digital Ground.

It got to the point where I considered that it might be easier to just buy some of the Canson or Hahnemuhle digital papers, which are their watercolour and drawing papers already coated with a high quality digital ground, though there’s a certain feeling of accomplishment taking the artisan approach of preparing your own media.

http://www.goldenpaints.com/mixmoremedia/digiground.php

http://www.canson-infinity.com/en/bfk310.asp

http://www.hahnemuehle.com/site/en/210/digital-fineart.html