FOR THE PERFECT VIEW
How to find the right glass for your picture frame
What's the difference?
A glossy glass is the most affordable standard for picture glass. It shows a perfect contour sharpness and is rich in contrasts - but: due to the smooth and shiny surface of the glass, the surrounding space is reflected when the picture is viewed in the glass pane and the joy with the picture is severely disturbed. If one wants to reduce the reflections in the glass, one often speaks of "anti-reflective" glass in colloquial language. This often refers to a picture glass with a matt, slightly textured glass surface. Precisely, there are two types of "anti-reflective glass":
With one-sided matt glass, the glass surface is roughened by etching the glass: the light is broken by the uneven glass surface, and the glass surface no longer appears glossy but matt. As a result, the image can be viewed glare-free. Further effects: the luminosity of colours or, for example, glossy areas in pictures or paper are lost to a certain extent. Since the effect increases as the distance between the glass and the picture surface increases, frosted glass is not suitable for DISTANCE magnetic frames.
Interference optically anti-reflective glass
The anti-reflective picture glass - often referred to as glass for museums - reduces the reflections in a different way: The technical term "interference-optically anti-reflective" refers to an optical coating that is achieved by a sputter process: similar to a spectacle lens, the glass surface remains smooth and reflections are reduced by the coating to less than 1%. The glass is completely transparent and the image remains true to the original without any interference. Anti-reflective glass is also suitable for DISTANCE magnetic frames. It is the optimal solution for unadulterated enjoyment of art and meets the highest demands of museums all over the world.
The video exemplarily shows the difference in reflection reduction between glossy normal glass, matt white glass on one side and museum glass.
The properties of glass and their effect on the picture are manifold. At this point, we provide a detailed overview of the various aspects that can and should be considered when selecting the "right" glass, which is also suitable for laymen.
The glass plays an important role for the picture: it separates the picture from the environment and the viewer of the picture. The tasks of a picture glass are manifold and range from protection against dust and contact to UV protection for the picture. At the same time, in the best case it provides an unclouded view of the picture and should preferably be invisible when viewing the picture.
1. My picture: glossy or anti-reflective?
2. Colour rendering: what does it mean?
3. What affects the contour sharpness?
4. Why do I need UV protection?
5. How heavy is the glass and frame?
6. What role does glass play in fire protection?
7. How sensitive is my glass to scratches?
8. How do I care for picture glass correctly?
9. How break-resistant is picture glass?
10. How are the glass edges processed?
11. How thick is the picture glass?
12. More information about glass?
Glossy or anti-reflective
The surface of the picture glass is of essential importance for the effect of the picture. Glasses are available smooth and glossy, slightly roughened or optically anti-reflective. The subject of reflection reduction should be considered and can be weighed individually on the basis of a few criteria.
Glass is not always glass. If it still seems the same at first glance, there are considerable differences when compared. Similar to the colour rendering index of a light source, picture glasses also have different effects on the authentic representation of colours in the picture, depending on the type.
If, for example, your image contains fine elements or text of low line width, the sharpness is more important than with large monochrome or white areas. There are clear recommendations and tips on what to consider when selecting glass.
The image, consisting of paper and paint, as well as our skin has a need for protection against harmful UV radiation. It is up to you to decide to what extent you want to protect your picture from aging by light. There are considerable differences between the glasses for pictures in this respect.
In the private environment the flammability of a picture frame will receive little attention, in buildings accessible to the public, preventive fire protection is one of the most important topics of our time. There are many possibilities for selecting glass, but there are still clear recommendations far away from or in addition to the standard.
They are not pretty and disturb the field of vision. A single scratch in the wrong place in the picture can seriously disturb the enjoyment of art. The sensitivity of glasses to scratches depends on the type and is directly related to the diligence in the care and handling of the glass.
The proper care is worth it. A picture glass is normally not exposed to excessive soiling. Nevertheless, the types of glass differ in their composition and there are some interesting suggestions and recommendations on this aspect for an unclouded enjoyment of picture and glass.
Glass is available for a wide range of applications. A picture glass should be at least 2 mm thick, preferably a little more, depending on the material and requirements with regard to stability and break resistance. The stronger the glass, the more stable it is. We have defined selected variants as standard for the individual grades.
Broken crockery don't bring you luck in this case. Resistance to breakage can be important to protect the image from damage by splinters and also to avoid injuries when framing a picture. From normal glass to safety glass, there is the right glass for all requirements.
Even today there are still a few framings in which a glass is inserted unpolished into the picture frame. That may be something everyone can judge for themselves. Glasses at HALBE are always machined and do not pose any risk of injury when framing or changing pictures - for safety first and foremost.
For experts, we provide know-how beyond the basic information and look forward to dialogue. No matter whether it is a question of data sheets or special requests: at HALBE you will always find an open ear for your concerns - from technical data to the offer of sheet goods for glass processors.
Once the picture has been hung securely on the wall, the weight of a picture frame no longer plays a major role. On the way there, please pay sufficient attention to the topic: be it when selecting nails or picture hooks, the load-bearing capacity of a rope suspension or with regard to the condition of the wall.
If you look at a picture, you want to look at it without being disturbed. Hardly anything can be as disturbing as reflections in the glass surface - be it with or without passepartout or even with a frame with integrated spacer between picture and glass. It is worth taking a closer look at the glass selection:
The effect of reflections can be observed particularly clearly when, for example, a window or a lamp is positioned opposite an image. Especially in this case, the finely matt white glass on one side is our tip as picture glass to reduce reflections. In this case, the anti-reflective glass can reduce reflections despite the optical coating, but it cannot completely block them out. If the "window problem" does not exist, then the glass for museums is the first choice for the anti-reflective coating of your picture in the frame.
A picture should be seen as unaltered as possible. This is especially true for the authentic representation of colors. Thus each picture glass offers a good view at first sight - with a trained eye and the love for details, however, there are remarkable differences in the self-coloring of picture glasses. Because glass is not identical to glass and there is picture glass for perfectly original colors cheaper than you might think.
Good colour reproduction ≠ Normal glass
Normal glass has a slightly greenish colour of its own. If you want to see the colours in the picture 1:1 and unadulterated, it is worth choosing a different type of glass in any case. There are perfect alternatives even for a small plus in budget. If, for example, you show a black-and-white photograph, a slightly greenish colouring of the bright picture elements would be particularly disturbing.
Colour-neutral view = white glass
The choice of a higher quality glass guarantees a colour-neutral view of the picture. The white glass has its name precisely for this reason: white remains white. And other colours also remain unadulterated. As a rule of thumb, the more you value the optical quality of your framed picture or the brighter the colours in the picture, the more important and better the choice of one of the following glasses: white glass, plexiglass, anti-reflective glass or Optium Museum Acrylic.
Choose a higher quality glass than the normal glass. You will have long-term pleasure if your picture shines in the best colours - a single small investment in the purchase of the frame, which is permanently worth it.
The finer and more detailed the motif or individual elements in the picture are, the more important it is to have a sharp look at it. Of course, the sharpness of the contours depends on the picture itself, but the surface quality of the picture glass also plays a major role.
How do I get the best contour sharpness?
The highest possible and best contour sharpness is achieved when the surface of the picture glass is smooth, not roughened. Disadvantage: With a smooth and shiny glass surface, the viewing suffers from reflections. The only exception here are anti-reflective glasses: the sharpness of the contours is maintained to one hundred percent, since the reflection reduction is achieved by an invisible coating instead of a roughened glass surface.
Are there any differences in matt glasses?
Glass experts speak of the gloss value in connection with the contour sharpness of structured, roughened glass surfaces: the higher the gloss value, the finer the structure of the roughened glass surface. This means that the finer the structure of the glass surface, the more perfectly the sharpness of the contours is maintained - while at the same time reducing reflections. HALBE anti-reflective glasses are always matt on one side and glossy on the other. So you can simply turn them over in the picture frame and use them either with an anti-reflective effect or with the glossy surface. So you can make your decision in peace after the purchase.
Due to its microfine structure, the one-sided matt white glass has the best contour sharpness among this type of glass. It is therefore recommended if there is a distance between the image and the glass surface - for example in combination with a 3 mm thick passepartout. The single-sided matt normal glass and the safety glass are more strongly structured than the white glass and thus appear slightly less contour-sharp. Plexiglas has the mattest, roughest appearance when used with an anti-reflective surface.
The solution for the greatest possible contour sharpness is provided by the invisible coating of the anti-reflective glass. Matt/glossy white glass is always a good choice and convinces with a great price/performance ratio, low reflection as well as high image sharpness and contrast.
The topic can be deepened scientifically very much, here a reduced and strongly simplified representation. As a general rule, papers and paints suffer from ultraviolet radiation and can be damaged over time.
Do I need UV protection for my picture?
It plays a role, which properties the paper and the colors of the picture show, how high the load is for the picture by UV rays in your premises and last but not least one must answer a central question oneself:
Do I present a picture worthy of protection, which should experience the best possible preservation of value or do I show a simple print, which can be reproduced without great effort if necessary. With an advertising poster or a do-it-yourself printout of the last holiday photo, the answer will usually be different than with an original work of art that requires a perfect conservation framing.
Each picture glass has its own characteristics. You always have to look at them in sum and weigh them up for yourself: if you want UV protection and at the same time value the best view, then Artglass AR 92, AR 99 Protect with high UV protection or Optium Museum Acrylic is the best type of glass for you. PLEXIGLAS® is a good choice if UV protection is the only priority and anti-reflective coating is not an issue.
Sometimes it plays a role that the picture frame should be as light as possible with regard to the handling during framing, hanging or with respect to shipping and logistics.
What to look out for?
The bigger the frame, the more the weight of the frame will be affected by the choice of glass type. For example, a single PLEXIGLAS® (without frame) is about forty percent lighter than a normal glass, while a safety glass is about fifty percent heavier. With smaller frame sizes, this is hardly noticeable; with larger formats, the difference will be several kilograms.
Decide what the weight means to you. In the frame configurator, the weight of the currently configured frame is always displayed as a calculated approximate value.
If you hang your frames on ropes, please observe the permissible working load of the suspension system. For hanging directly on the wall, there are different steel nails and angle hooks in the Halbe Shop. If you have any questions about weight and suspension, please do not hesitate to contact us personally.
If you want to hang up your pictures in public spaces, there are often regulations concerning preventive fire protection that have to be observed - i.e. the topic of safety and glass as an important aspect. As a rule, the "B1" requirements according to DIN 4102-1 must be fulfilled.
Which glasses fulfill the requirements?
All glass types meet these requirements - with the exception of PLEXIGLAS® and Optium Museum Acrylic. In this case, the only possible frame is a certified B1 magnetic frame made of aluminum.
Even though all mineral glasses meet the requirements, the best choice in terms of safety is toughened safety glass. It is significantly more impact and bending resistant than normal glass. And if it does break, it breaks into many small crumbs, which cannot injure you - sharp and pointed shards are eliminated.
In the private environment, the topic receives much less attention than in rooms frequented by many people. If you present your pictures in a public environment, ask the operator of the building about any existing requirements and guidelines for preventive fire protection.
The more carefully the glass is handled when framing or changing pictures, the better and more durable its surface quality will be - the correct care and cleaning of the different types of glass must also be observed.
In a nutshell and in product comparison
Mineral glasses without coating have a robust and insensitive surface - i.e. normal glass, white glass and toughened safety glass.
Scratch resistance of Artglass by Groglass
The museum glass from Groglass is definitely resilient to a certain extent, but the applied and baked-on layers for the optical anti-reflective coating are more sensitive than an uncoated glass. Even though the plasma coated surfaces are very stable, we recommend acting with greater caution here, as any scratches in the coating cannot be undone.
Scratch Resistance of PLEXIGLAS®
PLEXIGLAS® is known to be sensitive to scratches as a plastic glass. For protection during transport, PLEXIGLAS® is therefore always supplied with a protective film on both sides, which you only remove when framing your picture. This type requires the utmost care to avoid damaging the relatively soft surface. PLEXIGLAS®, which is glossy on both sides, is also available as a "scratch-resistant" version with an extremely robust coating on one side that is even more resistant to chemicals.
Scratch resistance of Optium Museum Acrylic
Optium Museum Acrylic is regarded as one of the best glazings for pictures worldwide: although made of plastic, it is abrasion-resistant and thus insensitive to supposed scratches. It is also antireflective, antistatic, lightweight, offers the best UV protection and great colour rendering - an all-in-one solution in museum quality.
The better the care, the less important the topic is. It certainly makes a difference whether you think about the finest scratches in the field of art or scratches caused by incorrect care and cleaning of a poster frame in retail stores. You are welcome to use the sample service and test the glass types in the original - so you can best compare all the properties of the glasses and make your decision: https://www.halbe-rahmen.de/en/service/samples/
A distinction must be made between mineral glasses and plastic glasses. There are also a few things to consider when cleaning coated anti-reflective glass as gently as possible.
How to clean the different glasses
Normal glass, white glass and toughened safety glass can be maintained with water or commercial glass cleaner. The surfaces are just as robust as the window pane at home. We recommend Cif Professional.
The museum glass from Schott requires a little more care than usual, as cleaning residues are more visible on the coated glass surface. To remove any streaks, use clear water or - for an even better result - Cif Professional glass cleaner.
A dry microfibre cloth is suitable for Optium Museum Acrylic, depending on the degree of soiling. In addition, the same recommendations apply as for the museum glass from Schott.
PLEXIGLAS® Gallery can be cleaned with water. The optimum solution for this grade to prevent micro-scratches and static charging is an antistatic cleaner with a special care cloth. As this is a special product, you can find it as an accessory in our online shop. https://www.halbe-rahmen.de/en/accessories/cleaning-and-care/
No matter which type of glass you use: Please always make sure that you never place a freshly cleaned glass into the picture frame or on top of the picture when it is wet. This can lead to irreparable damage to the picture. You will also find information on how to clean each type of glass in our overview of available types of glass here: https://www.halbe-rahmen.de/en/glass/information-about-glass-types/
The stability of the glass types differs significantly from one another. The breaking strength is usually considered in connection with the aspects of safety or transport risk. You do not have to worry about transporting from HALBE to you after purchase: Picture frames with glass from small to large are our daily business and we always make sure that the frames arrive undamaged by careful packaging and logistics.
Safety in matters of glass can mean two things
In the world of art and museums, it is important to protect the picture from damage caused by possible glass splinters. In school and kindergarten, for example, it is important to ensure that children are not injured by splinters or shards of glass.
Mineral glasses - without special protection
The mineral glasses have no special splinter protection. With a thickness of 3.0 mm, the HALBE glasses are more stable than the 2 mm thin picture glasses often used in many picture frames. Nevertheless, a normal glass will inevitably break if the mechanical load is too high.
Acrylic glass - light and unbreakable
PLEXIGLAS® is the best-known and most frequently used material to prevent the risk of injury from shards of glass. It is light and break-resistant - ideal if these two topics are important.
The same applies to the Optium Museum Acrylic, another 3 mm thick plastic glass. In addition to its breaking strength, it meets the most stringent requirements for conservation framing and is also available in 4.5 and 6 mm thicknesses for particularly large "XL" formats.
Laminated safety glass - maximum splinter protection
In the world of museums for many years the glass of first choice: Artglass AR 99 Protect by Groglass. The glass is a safety glass consisting of two letters with an inner foil. It guarantees a maximum of shatter protection and thus the best security against possible vandalism. In the event of a break, no fragments are produced and the image is not damaged.
Single-pane safety glass - impact-resistant without sharp edges
Last but not least: toughened safety glass is thermally toughened and thus significantly more impact and bending resistant than normal glass. However, if it breaks once, it breaks down into very small parts without sharp edges. The most common use for this glass is in combination with preventive fire protection.
Determine which properties are important to you for the picture glass in addition to the breaking strength. In most cases, it makes the selection easier if you prioritize the criteria for yourself and place their importance in a sequence.
Mineral glass is fireproof.
Acrylic glass is not fireproof, melts and starts to burn.
No matter which glass you buy from HALBE: there is never an unprocessed cutting edge that could injure yourself when handling the glass.
Glass edges of mineral glasses
All mineral glasses are cut on all four sides of the glass pane: normal glass, white glass, anti-reflective glass and safety glass. The shape of the cut is chosen so that the pane can be gripped comfortably and securely on the sides, slightly rounded, without sharp edges.
Glass edges with acrylic glass
PLEXIGLAS® and Optium Museum Acrylic are not ground, but sawn so straight and smooth that the surface of the pane remains perfect and undamaged all the way round. At the same time, the straight edge of PLEXIGLAS® is very easy to handle due to the blunt and non-sharp cutting edge.
If you do hit the glass during framing and a splinter comes off, be particularly careful. If the glass can no longer be used, all glasses in the HALBE Shop are also available as replacement glasses: https://www.halbe-rahmen.de/en/glass/replacement-glass/
The thickness of the glass depends on the type of glass you choose. In general, the stronger the glass, the more stable and heavier the glass. On the other hand, there are the optical properties of picture glass in various thicknesses and the question of the weight and handling of a glass pane.
Glass thickness of 3 mm
Normal glass and white glass have a thickness of 3 mm at HALBE. PLEXIGLAS®, Artglass museum glass and Optium Museum Acrylic from True Vue are 3 mm thick also. We have specifically selected these thicknesses as the optimum variants for your picture.
Exceptions are the following varieties
Optium Museum Acrylic with 3 mm
True Vue's Optium Museum Acrylic is usually used in 3 mm thickness. A big advantage of this type: If you want to realize large-format "XL" applications, the material is also available in 4.5 and 6 mm thicknesses. For the very demanding framing of large works, this means a clear plus in stability and flatness of the picture glass. We will be happy to advise you.
Laminated safety glass Artglass AR 99 Protect with approx. 4 mm
The museum glass Artglass AR 99 Protect by Groglass is 4.4 mm thick. It is a laminated safety glass, meaning a sandwich-like composite consisting of two AR 70 panes of 2 mm each, plus a film in between. This structure gives the glass a high degree of stability with a comparatively low thickness. It is mostly used in museums, where the focus is on perfect UV protection, antireflection coating and, above all, shatter protection and protection against vandalism for the image.
Single-pane safety glass with 4 mm
The single-pane safety glass is 4 mm thick. It is the thinnest glass thickness customary in the industry for thermally toughened glass. The weight of the glass is significantly higher than that of other types of glass. With a thickness of 4 mm, it is ideal for use as picture glass when a high degree of impact and bending strength is required. When used in the B1 magnetic frame for preventive fire protection, the glass benefits from its higher thermal shock resistance.
When you order your frames, we automatically take the glass thickness into account during frame production. So you always receive your frames with the ordered insertion depth suitable for the material thickness of your picture and/or passepartout - no matter how strong the glass is. If you order replacement glass for an already existing frame, please pay attention to the glass thickness of the old and the new glass. The HALBE team will be happy to answer any questions you may have.
The product descriptions and the properties of the individual types of glass can also be found in the glas category. You can select the type of glass for your magnetic frames in the configurator. As an accessory or spare part you can reorder individual glass panes in all types.
Do you need detailed information and expect expert knowledge like a transmission curve? Do you have further questions about glass or would you like advice for your personal application? Please do not hesitate to contact us.
approx. 3.5 kg per m²
approx. 7.1 kg per m²
approx. 7.1 kg per m²
approx. 9.5 kg per m²
VSG / Artglass AR 99 Protect
Protectapprox. 9.7 kg per m²
approx. 7.1 kg per m²
f.l.t.r. Normal glass glossy, white glass matt on one side, anti-reflective glass
left: normal glass; right: white glass
Outside: Newsprint yellowed after two days; centre: area protected by plexiglass without discolouration.
left: normal PLEXIGLAS®; right: scratch-resistant PLEXIGLAS®
bottom: unpolished normal glass; top: polished normal glass, slightly rounded, without sharp edge
from top to bottom: White glass 3mm, PLEXIGLAS® 3mm, ESG 4mm, VSG 4.5mm