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All Things Ampersand

Painting on Panel: The differences between HDF and MDF

To continue our series about Painting on Panel, I’ve pulled together information on the differences between HDF or High Density Fiberboard and MDF, Medium  Density Fiberboard.  I realize these posts are rather on the technical side, so please post questions if you have them.  We are here to help you make good choices for the longevity and beauty of your art.  

Hardboard is most commonly associated with Masonite, as this was the first “brand” of hardboard invented by William Mason in 1942.  Hardboard is often confused with high density fiberboard (HDF) or medium density fiberboard (MDF).  Producers of these different panels use reconstituted wood (saw dust and chips) and use different methods for manufacturing that in turn produce panels that have different characteristics in terms of density and internal bond strength. One of the most significant differences between Hardboard and fiberboard panels (both MDF and HDF) is the method of manufacturing. MDF and HDF panels use a dry process method and use synthetic binders or formaldehyde based agents for binding the wood fibers.   In comparison, Hardboard uses a wet/dry process method that relies on the natural binders within the wood to cement the fibers together and make the wood solid. 
The wet/dry process used to manufacture Hardboard has several advantages. The wet process method produces a smooth-one-side (S1S) panel, while the wet-dry process produces a smooth-two-side panel (S2S). Both processes explode the wood particles using steam pressure, and float them in a large vat of water, which pulls out many of the naturally acidic agents within the wood. The wood fibers are then randomly aligned parallel to the surface, and using heat and pressure, are made into a solid core panel. Ampersand’s Hardboard also has an added overlay of a neutral aspen fiber layer.  This process allows a very uniform and very strong panel, making it one of the best substrates for painting, laminating, and construction.  While still a relatively light-weight panel, Hardboard has a significantly higher density compared to MDF panels with a much higher tensile strength and internal bond than MDF and most HDF panels.

Ampersand’s Hardbord is made using a proprietary manufacturing wet/dry process that produces a superior solid core panel of unequaled strength and longevity. Ampersand’s Hardbord is made from FSC (Forestry Stewardship Council) certified forests.  This third party audit system employed by Ampersand’s supplier ensures chain of custody forest management and fiber sustainability.  This is the most stringent accreditation in the industry. Our aspen fiber overlay provides a more pH neutral wood content and even uniform fibers. Ampersand’s Hardbord outperforms all other HDF’s and MDFs in the market with regard to moisture resistance and strength.   

As mentioned earlier, Ampersand’s Hardbord is made using the natural binders in the wood. No added formaldehydes (NAUF) are used in Ampersand’s Hardbord, providing a virtually VOC free panel.

What you need to know:
• Hardboard panels are probably the best value on the market for artists today.

• Tempered panels produced within the U.S. no longer have the topical oil content they once had.  However, very small amounts of tempering oil continues to be added to the integral fibers.  Linseed oil is the natural agricultural oil use in the manufacture of hardboard.
• Hardboard is more dense than MDF and HDF, making it less prone to warping while still lightweight.
• Hardboard is a very uniform and stable surface without a grain, making it easier and faster to prime.
• Only natural binders used.
• Provides a pressed steam ironed surface to create a smooth gessoed panel.
• Larger panels can become heavier.
• Flexibility of the surface requires thicker hardboard to be used for larger paintings.

Medium Density Fiberboards (MDF) and High Density Fiberboards (HDF) are engineered panels that are made through a dry process that completely breaks down the particles of wood and reconstitutes them into a new panel using heat, pressure and a binder.  One of the most common binders used in their manufacture is urea formaldehyde, leading to potential problems with out-gassing. MDF typically has a density of 600-800 kg/m³, as compared to hardboard, which has a density nearly double that of MDF (1,450 kg/m³). HDF panels come closer to the densities of hardboard but are still normally 10 lb/ft³ lower in density than hardboard, making them more porous and more prone to warping, especially in an 1/8” thin version.   More layers of sealing and gesso are required to eliminate the fiber raising that happens with MDF and most HDF’s on the market.   MDF and HDF technology is rapidly changing and we will see better MDF being produced without formaldehyde as the binder and MDF that is much more dense and less prone to warping in the future.
What you need to know:
• If using MDF/HDF, make sure to seal the surface with several coats of Gesso and a good acrylic seal like GAC 
• Even with cradling, there is a high potential for these panels to warp over time
• MDF is not a high-density board. Fibers are very porous, and have a tendency to swell when painted, leaving a very uneven surface.
• Lightweight and inexpensive.
• Original organic structure of wood completely broken down to allow for consistent specifications.
• Future potential – could be a good panel in the future as technology improves density and binding material used.
• Not a dense panel – high tendency for warping in thinner versions.
• Porous, therefore not easily primed.
• Forrmaldehyde based resins primarily used for binders.
• High acidic content.
• Fibers swell when gessoed.

There are more posts coming on this important content about panels.  Stay tuned for feedback from other art material manufacturers and conservators.  

All things Ampersand,
Karyn Meyer-Berthel
Artist & Social Media Specialist
Ampersand Art Supply

Click here to explore the full selection of Ampersand panels and tools.

Painting on Panel: Solid Wood versus Manufactured Wood Panels

Madonna and Child with Angels, Ferrarese, c. 1455, tempera on panel

Historically, rigid supports were used long before the adoption of flexible fabric supports. Most of the earliest icons still in tact from the 2nd and 3rd century are on wood panels. During the Renaissance a large portion of the paintings were also on solid wood panels. Italian painters were known to use poplar, while their Northern counterparts were using oak (later they would move on to mahogany). The wood was first dried well and sanded very smooth. It was then covered with a layer of liquid gesso made by mixing gypsum (a white chalk pounded into powder), with glue made from animal skins. Then, the wood panels were sanded and burnished until they were smooth, and ready for painting. The fact that we still have so many of these paintings with us today is proof that a properly primed and maintained panel withstands the test of time. 

Traditionally solid wood panels were used in the Renaissance and continue to be used by some artists today. There is a great variety of solid wood panels, so it is important to choose one that is rigid, has a uniform grain, and has a low acidity. Avoid painting on softwoods or semi hardwoods such as pine or poplar. These woods are more porous, making them more susceptible to warping, and also have a higher acid content. Due to the potential for warping, a solid wood panel should be at least 1″ thick. It is also important to note how the panel is cut. A radially cut panel will have the grain running perpendicular to the face of the panel, and thus will be more stable than the more common tangentially cut panels, whose cut along the grain will tend to cause warping or twisting over time. In addition, solid panels cannot be braced (cradled) on their back. Due to the varying rates of expansion and contraction across a panel, a rigid bracing would actually cause the panel to buckle and bow in order to constrain to the bracing system.

While the original panel paintings were all made on solid wood panels, there are many more options available for artists today. Technology has created numerous types of manufactured panels, engineering them to have very specific attributes, and eliminating some of the original weaknesses in solid wood panels. A solid panel still has all the original cellular structure of the tree from which it was made. This structure is susceptible to expansion and contraction as the wood is exposed to different climatic and environmental changes. For example, over time wood can warp or split moving from wet to dry climates. Manufactured panels in contrast, break down the cellular structure of the wood, enabling a more uniform, stronger, and stable panel that can weigh less.
Unlike the masters of the past, the modern painter has numerous choices available when it comes to choosing a panel for painting. Four of the main factors to consider are a panel’s:
1.    Density: The denser a panel, the less moisture it will absorb, making it less likely to warp. It is also easier to prime because the wood will not absorb the primer as quickly, reducing the amount of layers needed to seal and coat a panel.
2.    Grain: If a wood has a heavy grain, it will require more layers of gesso to ensure that the grain does not come through the coating. Also, within the same type of wood there can be great variations in density along the lines of the grain. Woods can grow more or less dense with varying temperatures through the year, or even in ‘stressful times’ such as drought, and this varying density can cause warps or cracks along the lines of the grain.
3.    Acidic Content: Considering the acidic content of the panel is important in order to avoid SID (Support Induced Discoloration – or yellowing). Softwoods or semi hardwoods, such as pine or poplar, generally have a higher acid content, and are more prone to causing SID through leaching. Hardwoods generally have a lower acidity, though we’ll see there are exceptions to this rule. It is best to do some research to determine what is the acidic content of the wood you are using before beginning to prime a panel.

4.  Type of Engineered Wood:   While engineered wood such as hardboard, plywood, and MDF can offer substantially better dimensional stability over solid wood panels for artists, it is important to understand the pros and cons of each of these surfaces and how different panels are braced.  In upcoming blogs we will discuss these differences and the differences in the materials used to brace panels.

There is a lot more to come on this topic, so stay tuned for more in the series:  Painting on Panel.

All things Ampersand, 

Karyn Meyer-Berthel 
Artist & Social Media Specialist 
Ampersand Art Supply 

Click here to explore the full selection of Ampersand panels and tools.

Painting on Panel: Working with Masonite

With a lot more wood panels being sold in the market, some that seem less expensive and some that have different properties than Ampersand panels, I thought it time to share a series of posts on painting on wood panels.  In the upcoming months, I’ll share interviews with conservators and researchers, painting companies and artists about working on panels as well as scientific research on the differences in types of panel.  Please engage with us and let me know your questions so that we can guide you to finding the best surface for your art.

We often get questions about  the archival properties of painting on Masonite. To begin, the word “Masonite” is a brand name for “hardboard”.  It has been commonly known as “masonite” after the founder of the Masonite Corporation, William Mason invented this wood product in 1924.  These tempered hardboards in the 40’s and 50’s made conservators leery of paintings done on these now outdated hardboards due to the adhesion problems caused by the excessive oil on the surface. However, over 20 years ago, the high cost of tung and linseed oil forced U.S. manufacturers to change the way they manufacture hardboard. Today’s U.S. hardboard is no longer made by immersing panels in oil.  Instead, a tiny amount (less than .02 per sq ft) of oil (normally linseed) is applied with a roll coater and then baked and pressed at high temperatures.  Most of this oil is flashed off when the boards are baked. This oil “tempering” is invisible and does not leave an oil residue on the panel that can cause adhesion problems, as did the outdated hardboard. The purpose of this process is to make the board stronger and less prone to warping.

Mark Gottsegen, in his book, A Manual of Painting Materials and Painting Techniques, writes that both tempered and untempered hardboard can be used successfully for painting.  
However, when artists call Ampersand we always recommend using tempered hardboard because it will resist warping and the edges won’t fray as they sometimes do with untempered or standard hardboard.  Furthermore, tempered hardboard creates a better seal with oil and acrylic primers so that the painted surface is protected from any potential discoloration.

Ampersand uses a tempered hardboard as the base for its Museum panels. After extensive research and testing, we chose hardboard that is made through the Wet/Dry method. The Wet/Dry process method removes the lamella that contains many of the lignins and tannins that can cause discoloration in a painting over time. Through the use of water, this process leaches out many of water-soluble chemicals and acids that exist in the wood, leaving a more inert surface than a solid wood panel. No additional additives are necessary in this process because the natural wood fibers are used for binding, resulting in a stronger, more uniform, and denser board.  The Ampersand Hardbord™ is primarily manufactured from Aspen trees that have more uniform fibers and have more of a neutral pH than that of other woods.

Lastly, our hardboard supplier does not use urea-formaldehyde glue in the manufacturing process. They rely on the natural lignin in wood for the bonding of the wood fibers, making our board environmentally sound. 

Before closing I should  note that often MDF is sometimes referred to as Masonite or hardboard in lumber yards or even in art supply stores.  Artists should ask if the panel is a true hardboard and not an MDF.  Today there are very few true hardboard suppliers as the trend has shifted to MDF (medium density fiber) panels that are less expensive to produce.   However, the densities you can achieve in the hardboard process are difficult to achieve in MDF manufacturing without going to thicker heavier panels.  You will often see fiber raising and high levels of porosity in MDF’s.   

All wood surfaces should be sealed with a good primer before gessoing or painting on them. 

For more detailed and technical (believe it or not) information on hardboard and Hardbord, please refer to our website:  ampersandart.com/tips/archivalinfo

All things Ampersand, 
Karyn Meyer-Berthel 
Artist & Social Media Specialist 
Ampersand Art Supply 

Click here to explore the full selection of Ampersand panels and tools.