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All Things Ampersand

Painting on Panel: Support Induced Discoloration

You may have heard the term “Support Induced Discoloration” or SID in relation to sealing panels or even gessoing a canvas.  And SID is the one reason that Ampersand encourages sealing panels before priming, but what does it really mean and how does it effect art long term?

Support Induced Discoloration is a relatively new concept to the art world, new because acrylic dispersion paints are new.  Support Induced Discoloration occurs when acrylic paints change color due to pulling up toxins or residue in the substrate.  The fluids in the paint leach into the substrate, through the primer and pull up the residue, leaving behind particulate in the paint that discolors it.  This is most apparent in transparent gels and mediums but also occurs to pigmented paint.  Gesso or primer is not sufficient in preventing discoloration, so sealing or sizing is always recommended.  

You can prevent SID from affecting your own work by properly sealing wood panels before use.  For more information on Sealing (or sizing) panels, refer to our previous post:
Painting on panel sizing.  OR, You can purchase one of Ampersand’s already sealed and primed panels, such as Gessobord™, Encausticbord™, Claybord™, Aquabord™ or Scratchbord™.  All of these panels have been sealed with Ampersand’s Archiva-Seal™ technology.

In the early 1990’s, Golden Artist Colors did some significant research with Buffalo State College to discover support induced discoloration and test the degrees of discoloration on different supports, with different acrylic mediums and primers.  The results from these experiments led to what we know today about SID.  

“SID contamination often goes undetected. In most cases, the paints applied contain a sufficient level of pigment, thus a strong enough color, to conceal the yellowing. However, in a transparent glaze and especially in thick translucent gel layers, SID becomes quite noticeable. SID can transform the appearance of an Ultramarine Blue glaze into a lower chroma, greenish color. Gesso alone will not stop SID, and different gels and mediums have varying degrees of blocking capabilities. The best product Golden Artist Colors produces to prevent SID is GAC 100. This thin medium works best when 2 or more coats are applied directly into the support. Once dry, the canvas can then be primed and subsequently painted with less potential for discoloration. Pre-primed canvases can be sealed with GAC 100 as well. Apply one or two coats onto the surface, and follow with at least one coat of gesso to regain tooth if needed.” — From the GAC website

Golden has neatly packaged the effects of SID on a masonite panel below in video format.  You can see for yourself in a few minutes how drastically a piece of art can change in a matter of weeks if the work is not sealed properly.


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: Acrylic Priming

We have reviewed how to size and seal wood and how to prime it with oil primer.  Some of you may prefer to use an acrylic primer, or an acrylic dispersion ground for you work.  Our best recommendations for the process are below.  

Golden® brand acrylic gesso is our first recommendation.  However, these instructions are virtually interchangeable with a number of other brands if there’s one you like better or have more readily available. Gesso is a flexible liquid ground that seals, protects, and gives “tooth” to wood panels, which promotes good paint adhesion. It comes ready-to-use, but can be mixed with water for thinner applications. Golden® Gesso is available in Black or White, and can be mixed with Golden® Acrylics to produce a range of colored grounds. Gesso can be applied with a brush, roller, putty knife, Catalyst™ wedge #W-06 or sprayed on. Dilution of the Gesso is only necessary for spray application, but may be desired for brush or roller applications as well. When diluting with water, use a maximum dilution of 25%. Any mixture within this range offers little risk of cracking or other adverse effects.

Step 1 – Size and seal the wood
A size is a thin solution (often a weak glue) that is brushed directly onto a support. Sizing or sealing is recommended to protect Ampersand’s uncoated panels from support-induced discoloration when using acrylic gesso. If wood is not sized or sealed properly before applying the gesso, yellowing can occur because water [a solvent] can cause acids, occurring naturally in wood, to migrate to the surface. In fact, it is extremely important to properly seal any and all un-primed wood substrates to prevent support-induced discoloration that can cause your paint film to yellow over time. Hardbord™ is manufactured using Aspen fibers, a wood with a very low acid content, but still needs to be sized and sealed. The Natural Wood Panel™ and Unprimed Basswood panels are made with a thick basswood plywood top that has been sanded ultra-smooth. They are both seamless and knot-free and provide a perfectly smooth and uniform painting finish. When you size and gesso the basswood surface, you won’t experience the raised wood grain fibers that can happen with some other rougher types of plywood; the surface stays nice and smooth. The basswood panels have solid wood cradles and braces that may be more susceptible to moisture and environmental changes than the birch plywood cradles we use on the Hardbord™. Therefore, Ampersand recommends that you prime both the front and back of the Basswood top to ensure long-term stability of the panel.

The best products we have found to seal wood are Golden®GAC100 [2 coats]  and Gamblin® PVA Size [4 coats].
Apply Golden® GAC100 directly to the basswood or hardboard surface with a 2″ paintbrush or putty knife. Apply to the front and back if applicable. Allow the GAC100 to dry completely and follow with an additional coat. Do not sand between layers. Before applying oil primer or the painting ground, allow the GAC100 to dry for 1-3 days so that the sealer can coalesce into a uniform film for maximum protection. If you’re using Gamblin® PVA Size, use 4 coats and follow the same application instructions as for the GAC100.

Step 2 – Protect and prepare the cradle
Hardbord™ is available in either a flat 1/8″ panel, with a 3/4″ cradle, or with the 2″ DEEP cradle. The Natural Wood and Unprimed Basswood panels are available in both a 7/8″ cradle and 1.5″ cradle profile. You have the choice of painting all the way around the cradle or leaving the natural wood showing for framing purposes. Be sure to size and seal the bare wood if you want to paint completely around the edges of the cradle. Or, to protect the wood from paint and gesso, cover the sides of the panel with painter’s tape up to the edge of the surface. Do not remove the tape until the painting is finished. Painter’s tape does not leave a sticky residue like many household masking tapes that can be difficult to remove, and will leave a pristine surface underneath when the painting is complete. For instructions on different ways to prepare your cradles for presentation, consult this article: https://ampersandart.com/featuredartist/featured-artist-pramuk1.html

Step 3 – Apply the Acrylic Gesso

Thin the gesso with up to 25% water for the first coat so that it will flow more evenly on the [sized] panel. Use a 2″-3″ brush for the first coat and a foam roller for subsequent coats. Begin by working the gesso back and forth with the brush in one direction and then in a cross direction with a little pressure so that the gesso penetrates the panel better. Apply gesso to the side edges of the panel and the plywood cradle if applicable. Don’t forget to seal the cradle with Golden® GAC100 first if you are going to gesso the edges for painting. The basswood panels have solid wood cradles and braces that may be more susceptible to moisture and environmental changes than the birch plywood cradles we use on the Hardbord™. Therefore, Ampersand recommends that you gesso both the front and back of the basswood top to ensure long-term stability of the panel. Allow the front of the basswood to dry completely, then, gesso the reverse side.
Step 4 – To Finish
After the first coat of gesso is dry, smooth out any rough spots with light grade sandpaper. Apply a second coat of gesso with the foam roller (or brush). Allow it to dry and then sand again. For best results, apply a minimum of 2 coats of gesso and sand in-between. Subsequent layers of gesso will produce an even smoother painting surface. For spray-application, you may have to apply more than 2 coats to achieve a film similar to a brush application. For basswood panels, follow the same instructions, but also prime the back. For each additional coat to the panel face, apply the same number of applications to the panel back.

The fall sale is on!  Hardbord, Gessobord, Claybord, Encausticbord and all Artist Panels are all on sale, 20% to 60% off at a dealer near you!

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: Oil Priming

For those of you that purchase our museum quality panels, Aquabord™, Encausticbord™, Pastelbord™, Gessobord™ or Claybord, we complete the sealing and priming for you on the front of the panel.  However, for anyone who is choosing to do their own sizing and priming for oil painting, these instructions for priming in oil will be helpful.  Our Hardbord panel and the Unprimed Basswood Artist Panel both require sealing and priming before use.

All wood panels must be sealed (also known as sizing) before painting in order to put a barrier between the naturally occurring chemicals in wood and the painting ground. Support Induced Discoloration (SID) occurs when a panel is not properly prepared and these chemicals leach through to the paint on the surface. By choosing a denser panel with a low acid content, an artist greatly reduces their risk of SID. However, all wood panels should be sized (sealed) and primed before painting to ensure their longevity. 

Gamblin® Oil Painting Ground is our first choice in a good quality oil primer. However, the following instructions are virtually interchangeable with a number of other oil painting grounds if there’s one you like better or have more readily available. Gamblin® Oil Painting ground contains an alkyd resin vehicle that allows it to dry within a matter of hours. A number of other pre-made oil primers are also available and generally, they are made up of a white pigment, linseed oil and driers or solvents. Primers that use alkyd resin binder instead of linseed oil dry faster and are non-yellowing and more flexible than traditional grounds. Both may be applied in the same manner with either a large putty knife or a large stiff bristle brush. If you are using a traditional oil primer, it may need to be thinned with Gamsol® to a workable consistency enabling easy application over the sized panel. Never add oil to a primer. Its leanness must always be preserved.

Step 1 – Size and seal the wood
A size is a thin solution (often a weak glue) that is brushed directly onto a support. Sizing or sealing Ampersand’s uncoated panels is recommended to protect against SID. In fact, it is extremely important to properly seal any and all un-primed wood substrates to prevent support-induced discoloration that can cause your paint film to yellow over time. Hardbord™ is manufactured using Aspen fibers, a wood with a very low acid content, but still needs to be sized and sealed. The Natural Wood Panel™ and Unprimed Basswood panels are made with a thick basswood plywood top that has been sanded ultra-smooth. They are both seamless and knot-free and provide a perfectly smooth and uniform painting finish. When you apply the size and primer to the basswood surface, you won’t experience the raised wood grain fibers that can happen with some other rougher types of plywood; the surface stays nice and smooth. The basswood panels have solid wood cradles and braces that may be more susceptible to moisture and environmental changes than the birch plywood cradles we use on the Hardbord™. Therefore, Ampersand recommends that you prime both the front and back of the Basswood top to ensure long-term stability of the panel.  The best products we have found to seal wood are Golden® GAC100 [2 coats]  and Gamblin® PVA Size [4 coats].
Apply Golden® GAC100 directly to the basswood or hardboard surface with a 2″ paintbrush or putty knife. Apply to the front and back if applicable. Allow the GAC100 to dry completely and follow with an additional coat. Do not sand between layers. Before applying oil primer or the painting ground, allow the GAC100 to dry for 1-3 days so that the sealer can coalesce into a uniform film for maximum protection. If you’re using Gamblin® PVA Size, use 4 coats and follow the same application instructions as for the GAC100.

Step 2 – Protect and prepare the cradle
Hardbord™ is available in either a flat 1/8″ panel, with a 3/4″ cradle, or with the 2″ DEEP cradle. The Natural Wood and Unprimed Basswood panels are available in both a 7/8″ cradle and 1.5″ cradle profile. You have the choice of painting all the way around the cradle or leaving the natural wood showing for framing purposes. Be sure to size and seal the bare wood if you want to paint completely around the edges of the cradle. Or, to protect the wood from paint and primer, cover the sides of the panel with painter’s tape up to the edge of the surface. Do not remove the tape until the painting is finished. Painter’s tape does not leave a sticky residue like many household masking tapes that can be difficult to remove, and will leave a pristine surface underneath when the painting is complete. 

Step 3 – Apply the Oil Painting Ground or Oil Primer
Begin by mixing small amounts of Gamsol® with the primer to thin if necessary. You can test the right consistency by picking up the paint with a knife and shaking it gently. If it falls from the knife like soft butter, it is ready to use.

When priming with a putty knife [or wedge tool], begin by placing a portion of the oil painting ground or primer in the center of the [already sized] panel. Spread it in one direction, and then in the opposite, and finally in a diagonal direction. Clean the putty knife and run it over the ground to smooth and even out the surface. Also, prime the edges of the panel and the cradles if applicable. Don’t forget to apply GAC100 on the cradle edges first if priming them for painting. 

When the first coat of oil painting ground is completely dry (about 7 hours), lightly sand the surface with a sanding block using light grade 400/grit sandpaper. A second coat can be applied the next day or any time after the first coat is dry. If using basswood, for each additional coat to the panel face, apply the same number of applications to the panel back.

If priming with a brush, use a large bristle brush, at least 2″-3″ wide (proportionate to the size panel you are using), and apply the ground or primer with quick alternating strokes, working it well into the surface. After evenly distributing the ground or primer over the entire surface, finish by going over it lightly with a clean brush, carefully in straight lines, or use a short-nap [cotton] roller. Let the first coat dry, then sand and apply a second coat. At least two coats of ground or primer should be applied. The more coats of ground or primer that are applied, the smoother the surface will become. For basswood panels, follow the same instructions, but also prime the back. For each additional coat to the panel face, apply the same number of applications to the panel back

Step 4 – To Finish
Eliminate any unevenness on the finished primed surface by lightly sanding the panel after it has thoroughly dried. The finished primed panels should be allowed to dry completely at room temperature before painting. If you prepare several panels at a time, then you will have stock on hand that is dry and ready to paint when needed. 

Below is a video produced by Gamblin with Scott Gellatly, technical director, explaining how to prime a painting.



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: 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.
Pros:  
• 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.
Cons:
• 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.
Pros:
• 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.
Cons:
• 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: 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.