Shading agents

Document Sample
Shading agents Powered By Docstoc
					        Shading agents



• Spuitfix
• Whitefix
• Shadefix
• Transfix
• Q4 White (NEW)
• DPF Black (NEW)
Theory
An important subject for growers in greenhouses is light, that’s because plants won’t grow without light. The
sunlight that enters the greenhouse is for free and that’s why we want to use as much of it as possible. Too much
light can cause damage to the crop therefore most growers use a shading agent on their greenhouse.



Light
The basics of light is the wavelength. The light that humans can see is only a small part of all
the light that reaches the earth. This little part consists out of the wavelengths 400 – 750 nm
and represents all the colours in the rainbow.
The light as humans see it is called LUX light. As the graph shows humans see a lot of
green and yellow light compared to all of the other colours. For plants the peaks in the graph
are totally different. Plants see a lot more red and blue light and this is called PAR light
(Photosynthetic Active Radiation).
                                                                                                         LUX light

Diffused light
When light enters a glasshouse, it does so in a straight line. We are now able to apply a shad-
ing product which can diffuse the light as it enters the glasshouse. By diffusing the light, we
are spreading the light in every direction inside the glasshouse, resulting in it reaching places
within the crop that light would not normally reach. This gives more efficient photosynthesis,
resulting in better growth and higher yields. The rate at which light enters the glasshouse is
called the ‘haze factor’ - the higher the ‘haze factor’, the more diffused the light is.

                                                                                                         PAR light

Shading
To prevent the crop from being damaged, a shading agent is sprayed on to the glasshouse roof to reduce the intensity of the
light. The traditional products used were powders which stuck to the glasshouse, but more recently liquid formulations have
appeared making application and removal much easier for the grower.



Shading agents in to practice
Every crop is different - some require much more shade than others, meaning in practice many different rates can be re-
quired. The lower the % of shading required, the more light allowed to enter the glasshouse.

Dosage
It is much easier to adjust the application rate of a liquid shading agent, than
it is with a powder. Normal shading requirements will vary from 25% to 80%
shade, as measurements higher or lower than this have shown to have little
significant different effect on the crop. Perecentages of shading are expressed
as percentage of LUX.



Application
Shading agents are applied by mixing the liquids with water to give the desired application rate - the amount of water re-
quired can vary from product to product and the label should always be checked. When mixing the shading agent, it is best
mixed in 75% of the total water required, then topped up to 100% of water, and applied to the glasshouse immediately.
Wear away
The different shading percentages also influence the amount of wear off during the
season. When shaded with a minimum percentage the wear off during the season
will be greater than when shaded with a high percentage, for example 80%. The wear
off of the shading agents starts at the top of the greenhouses, as seen in the picture.
This is because this part of the greenhouse is most vulnerable for the elements. This
wear off is unwanted because the light that still enters the greenhouse can be too
strong for the crop. This is the reason that most growers apply a shading agent a
second time during the season, which is expensive.

                                                                                                    Example of wear away
Products
Fixen
The “Fixen” products are powdery shading agents which differ from each other in durability. The Fixen are based on starch
flour which attaches to the glass. The more starch flour the better the durability. Because of the difference in product there is
a “fix” for every shading problem. The Fixen are widely used by growers of flowers and potted plants.

 Products                                    Durability
 Spuitfix                                    Short, wears off after some rain**
 Whitefix                                    +/- 2 months**
 Shadefix                                    3-4 months**
 Transfix (transparant when wet)*            6-7 months**


* Transfix needs to be brushed off for removal.
** Depending on the weather conditions. In area’s with low rainfall the durability can be longer.

Spuitfix
A powdery shading agent ideal for short time shading requirements. Wears off after a few showers. No remover required.

Whitefix
A rainproof powdery shading agent with a low starch flour concentration, which results in a durability of about 2 months.
Whitefix can be removed with Greenhouse Clean CC.

Shadefix
Shadefix is rainproof with a durability of about 3-4 months. Shadefix differs from competitors in:
-       Better light and heat reflection because of a higher whiteness
-       100% environmentally safe
-       Raw materials are 100% natural
-       Easy to mix
-       Easy to remove with Greenhouse Clean CC

Transfix
A liquid shading agent which turns transparent when wet. Because of this transparency 2-3 times more light reaches the
crop during rainy days. Transfix has a durability of 6 months and can only be brushed off.
          Liquid shading agents
          Liquid shading agents are now widely used because of the ease with which the shading % can be adjusted. As a result,
          liquid agents are far better in climates with moderate sunlight levels (Northern Europe) - climates with high sunlight levels
          and higher UV levels and less rainfall (southern Europe) are more suited to the ‘fixen’ products (powders). Liquid shade
          agents should last 4-5 months on the glasshouse roof depending of course upon application rate and weather conditions.
          Removal is simple with the removing agent.

          Q4 White
          After several years of testing in Europe, the new Q4 white is now commercially available. Q4
          white is a liquid shading agent which is an alternative and competitor to the longer established
          ‘Redusol’. Q4 white is applied in exactly the same way as Redusol, with similar dosage and
          application rates, and to keep things simple, the cleaning agent (Q4 white remover) is also
          applied at the same rates as Reduclean (1:7). In tests over the past few years, Q4 white has
          shown to be more durable than its competitors on the apex of the roof, and as a result second
          applications have not been necessary.

          Advantages
          -         Minimum wear off on the apex of the roof
          -         Competative pricing
          -         More weather resistant
          -         Diffuses light
          -         Adjustable shading %
          -         Easy to remove with Q4 White remover

          DPF Black
          DPF Black is a shading agent with an extra ingredient added to make the product darker.
          This darker shade is unique, and hence is suitable for crops needing dark conditions (eg
          Phaleanopsis). It also has a high heat reduction capacity, and will therefore give much cooler
          conditions compared to any white shading agent. It is also ideal for retail areas or packing
          areas where staff comfort is important and cooler conditions are required.

          Advantages
          -         More weather resistant
          -         Maximum light- and heat reduction
          -         Minimum wear off on the apex of the roof
          -         Adjustable shading %
          -         Easy to remove with DPF Black remover




                               Difference between Q4 White                                      Manual application of Q4 White
                                   and DPF Black (dark)




03-2011   Brinkman International BV - PObox 303 - 2690 AH ‘s-Gravenzande - Tel. (+31) 174 - 446 100 - Fax. (+31) 174 - 446 151 - Email: royal@brinkman.com

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:5
posted:8/4/2011
language:English
pages:4