BS 12404:2020 pdf download – Durability of wood and wood-based products – Assessment of the effectiveness of masonry fungicide to prevent growth into wood of Dry Rot Serpula lacrymans (Schumacher ex Fries) S.F. Gray – Laboratory method
The carbon dioxide reduces the alkalinity of the mortar. The alkalinity of the mortar test specimenscan be checked with a phenolphthalein colouring method.Prepare a mass fraction of 1 % solution ofphenolphthalein in ethanol.Remove two dried mortar test specimens from the tubes and split themin half.Spray the phenolphthalein solution on the cut surfaces.If a red colour develops the mortar testspecimens need further curing. When the colour of the cross sections remains unchanged the mortartest specimens are ready for further preparation.
7.4 Leaching of mortar test specimen
Immerse the cured mortar test specimens(7.3) in deionized water for two weeks. Use 300 ml water permortar test specimen and change the water twice per working day.
After this leaching period,fill each tube with a 100 mm high water column and record the time taken forthe water to pass through the mortar test specimen. Reject specimens with a time of greater than 90 s.Store the acceptable mortar test specimens for at least two weeks in the conditioning chamber(5.3.5)before continuing with the testing.
7.5 Number and distribution of mortar test specimensDistribute the mortar test specimens (7.4) as follows:
-treated mortar test specimens:
use at least 10 mortar test specimens for each combination of concentration and application rate.untreated control mortar test specimens:
use at least 10 control mortar test specimens.
For the testing, on each of the acceptable mortar test specimens slide a length of tubing (5.3.3) over theend of the rigid tube remote from the mortar so that one end of the tubing coincides with the end of therigid tube remote from the mortar.Insert the tubing covered tube through the hole in a screw cap froma culture vessel (5.3.1).
Place the mortar test specimens in the rack (5.3.13) (see Figure 1).
8 Wood test specimens
8.1 Species of wood
The following wood species shall be used for the test.Scots pine (Pinus sylvestris Linnaeus).
8.2Quality of wood
The Scots pine shall be exclusively sapwood containing little resin.
The wood shall be free from knots, cracks, stain, decay, insect damage or other defects.
The wood shall not have been water- stored, floated, chemically treated or steamed.
Wood that has been kiln dried at temperatures below 60 C can be used.
8.3Provision of wood test specimens
Cut the wood test specimen from planed strips having a cross section of (25±0,5) mm x(15±0,5) mm,in which the growth rings may run in any direction.
8.4Dimensions of wood test specimens
The dimensions,measured at a mass fraction of (12 ± 1) % moisture content, shall be (20 ± 0,5) mm(length) x (25±0,5) mm x (15±0,5) mm.
9.1 culturing the test fungus
Ilnoculate the culture medium in each culture vessel (5.3.1) not more than one week after sterilisationof the culture medium(5.2.2) and using stock cultures of the test fungus which are not more than fourweeks old.Store the inoculated culture vessels in the culture chamber(5.3.6) until the test fungus hascovered the surface of the culture medium; use within one week of this stage being reached. The testfungus shall not be visibly contaminated by other organisms.
9.2Treatment of mortar test specimens
Use the test preservative (see Clause 6) as delivered by the supplier or diluted into a container (5.3.9)according to the sponsor’s instructions. The application rate(s) shall be as recommended by the supplierbut shall not exceed 500 g/m2.Calculate the amount of preservative solution to be applied to eachmortar test specimen.Using a pipette, spread the treatment solution evenly over the mortar surfacewithin the tube; determine the exact amount applied by weighing before and after application.Returnthe treated mortar test specimens to the rack (5.3.13) and store in the conditioning chamber (5.3.5)for one week.
9.3Preparation of wood test specimens
Not more than one week before the fungus testing (see 9.5), impregnate the wood test specimens withthe nutrient solution (5.2.3), according to EN 113:1996,8.2.2.
NOTE The impregnation of the wood test specimens with a nutrient solution encourages fungal infestation.9.4Sterilization procedures
Put a wad of non-absorbent cotton wool in the top of the tube of each treated mortar test specimenand each untreated mortar test specimen. Screw the lids of each specimen into empty culture vessels(5.3.1) and close the lids to one quarter of a turn less than full closure.
Sterilize all the assemblies using an appropriate procedure for each preservative under test(see Annex B).
ln case of doubt on the heat sensitivity of the preservative, it is recommended to contact the supplier.Sterilize the water, the supports (5.3.4), the nutrient treated wood test specimens (see 9.3) and theforceps in the autoclave (5.3.8) for 30 min at (121±2) °℃.BS 12404 pdf download.