Hi, We have an old shed which needs to be given a treatment to protect it against high rainfall over winter and intense sun in summer. Limewash would be good but I wanted to recote the lime with a Linseed oil expecting that we will get a longer life from the application. Has anyone any experience with working with lime and then linseed? I'm told the linseed will make timber dark, and to mix it with turps. There are also old recipes that cite using boiled down rice water to help make the lime stick - whereas we think that any mix will need a second coat to 'seal' it. All comments welcome.
Using Lime-wash on old timber
(12 posts) (4 voices)-
Linseed on its own will make the timber darker, however used with the lime will increase adhesion.Hydrated lime is blended with water to produce whitewash. Rates -mix and test. Additives like water glass, glue, salt, soap, milk, flour, earth, egg white and blood have been used in white wash paint recipe. Adding earth can help to create different shades of whitewash paint like cream, yellow, browns. Sometimes linseed oil is added, for the whitewash to adhere on difficult surfaces. Cement is added to create a harder wearing gray or white paint. Many times, diluted glues are used to improve the toughness of the paint.
Posted Wednesday 5 Feb 2014 @ 9:46:01 pm from IP # -
Preparing Suitable Surfaces (Lime and Masonry)
The surface must be prewet (humidified) before each layer of wash is applied. Prewetting can easily be accomplished with a fine mist of water using such tools as a plastic spray bottle, pump sprayer or a garden hose with a suitable mist nozzle.
Prewetting the surface prevents it from absorbing water from the limewash itself, which could impair the critical carbonation process. A light dampness is desired — too much water on the surface will interfere with cling and coverage.In temperatures above 30 ºC or in very low humidity, surface and subsequent coatings must be misted with water.
Exterior coatings should be protected from wind and sun to protect from drying too quickly an opaque covering such as damp canvas or burlap works particularly well.
Surfaces must not have a surface temperature below 6 ºC (8 ºC for dark colors) and must not be excessively hot or excessively wet.
The most critical period of carbonation is the first two to three days.The limewash effect (visual appearance) is determined by the water to lime volume ratio, and can be divided into four distinct types. Each type corresponds to a unique recipe:
Liming Coat — a thicker application with a more opaque look
Wash — partially transparent, but with a strong coloring
Tempera — medium-transparent, with the surface effect of tempera paint
Patina — strongly transparent with an aged look
Water to Lime Ratios by Volume:
Ingredients Liming Coat Wash Tempera Patina
Lime Powder 1 1 1 1
Water 1 2-3 4-6 10-20For limewash, pigments are added after the water and lime are thoroughly mixed. Slake (wet) the pigment in an equal amount of water to form a paste. This paste can be left to soak overnight if desired. Add the pigment paste to the limewash and stir — an electric paint paddle is recommended for complete dispersion. How much pigment you add depends upon individual pigment density, intensity of color desired, and chosen recipe.
Here when referring to a maximum percentage of pigment, we mean the saturation limit. Beyond this percentage, the pigment no longer adds intensity of color but instead begins to thicken the mixture, increasing the load that is to be fixed by the lime. Therefore, too high a percentage of pigment will result in mechanical failure of the limewash. The chart below lists limits for Earths, Ochers and Oxides. Note that as the volume of water in your limewash increases so can the weight of pigment before saturation occurs. Use this as a guide — these are upper limits; you can use less than indicated.Maximum percentage for Earths/Ochers/Mineral Pigment in relation to lime powder by weight (For Natural Yellow, Natural black and Natural red use instead the maximum percentages shown for Oxides.)
Liming Coat Wash Tempera Patina
10% 22% 65% 95%
Maximum percentage for Oxides in relation to lime powder by weight
Liming Coat Wash Tempera Patina
5% 15% 35% 55%Additive Binders for Enhanced Adherence
Resins such as linseed oil
Glues such as casein or methyl cellulose
Modern binders like PVA, (polyvinyl acetate)
Linseed Oil is inexpensive and natural but it will alter the matt (flat) quality of a limewash, (it will also yellow over time).
Casein is inexpensive, natural and will not alter the matt quality of the coating. Prepare by soaking in hot water at a ratio of 1 Kgs casein per 3.4 litres of water. Allow mixture to stand overnight.
Methyl Cellulose is a plant-based glue. It is inexpensive, and has the additional benefit of enhancing water retention. This slowing of the drying process is especially important in dry, hot or windy conditions where drying too quickly in the first two or three days can interfere with the important carbonation process. Do not use in wet conditions or on overly wet supports. Preparation: 20 grams per gallon of water. Allow mixture to stand overnight. It is the weakest of the binder additives, and really serves more to extend the "open time" of the limewash so that it does not dry too quickly in dry or hot conditions.
PVA, (polyvinyl acetate) is strong and inexpensive. We recommend our Acrylic Binder - a superior product that, unlike other PVA products, dries crystal clear. Dilute the proper amount with some of the water used from the chosen recipe then add to the remaining limewash mixture.
Additives are added after the initial mixing of the lime and water at a ratio of 1 to 10% of the volume of prepared limewash, before adding pigment. These additives can enhance binding strength and thus help to overcome less than perfect surface and application conditions. They can also assist in stabilizing the pigments within the limewash mixture. Since these are positive effects, their use is fairly common. However, these additives will also affect the porosity of the final lime coating, and a decision on whether to use them or not should take this fact into account.
One important rule: always add the same ratio of additive binder for each successive coat. Also, never exceed this 10% volume ratio as your limewash will no longer be a lime coating, but will primarily become a distemper paint.Application Techniques
It is best to test your mixture to be sure ratios are correct and that, when dry, the desired color and effect has been achieved. Dry color will be lighter than when wet. Limewashes also will dry to be more opaque than when wet, so do not make the mistake of applying too much in one coating.
Several thin coats are the key to limewash success — never apply too thick. For exteriors, 5 coats is recommended. For interiors, 3 coats should suffice. Lime is hard on brushes so choose a longhair masonry brush, ( For mixing, the use of an electric paint-mixing paddle is recommended, along with rubber buckets, rubber gloves and eye protection. Mix only the amount of limewash to be used in one day.Secco or "dry application" for cured surfaces: prewet the porous surface and allow it to sit several hours or overnight. When applying, do not spread the wash out as you might do with paint — apply with an even stroke and pressure to work the wash into the surface. Stir the wash between strokes. Water can be added to dilute the thick layer of wash that will be found at the bottom of the bucket as the wash is used. Apply your strokes vertically, then horizontally, finishing with a vertical stroke. When applying successive layers, allow the limewash to dry for 1 to 3 days between coats. Mist the surface with water and use slightly higher ratios of water with each successive coat — this ensures good adhesion and carbonation.
Recipe Guidelines
Liming Coat
A thicker limewash is often used as a maintenance coat on interior or exterior masonry. Since it is thicker and more opaque than a wash, brush strokes will be apparent. Be cautious about using this recipe — although at first it may seem to cover better and be successful without all the work of several thinner coats, liming coats can easily be applied too thick which will result in failure due to poor application technique.
1 part water
1 part lime powder
Additive binder at a ratio to the total volume of limewash mixture at no more than 10%
Pigment by weight (ratio to lime powder) of no more than 10% Ochers, 5% Oxides maximum
Wash
A wash has less texture than a liming coat, but still masks the surface. To obtain the best result, stir between every stroke.
2 part water
1 parts lime powderI think that should give you something to go by...
Posted Friday 7 Feb 2014 @ 12:01:49 am from IP # -
ankerre
MemberEamon, this is an excellent posting so thanks for all the info. Am working my way forward on this project slowly.
Not sure if it does apply to the job I have as it is a timber shed, quite large in size - your headings seem to indicate that the information pertains to masonry. The shed we have was painted maybe 30 years plus ago, and much of the paint has come off. So, we have predominantly bare timber - I expect I need to give it a light sanding before any application. Previous paint only barely visible. So, my question is - does your various recipe's transfer to use on timber? Also, my local supply merchant has AGL (agric ground lime) and hydrated lime - I assume I need the latter. Cheers.Posted Saturday 8 Feb 2014 @ 4:43:30 am from IP # -
Morbo
Memberis the timber still good, some years without paint? Sand everything dead off, using orbital sander and proper sandpaper. I got a Ryoby one with 150mm disk, sandpaper I got from a place that sells floor sanding products, fabric with velcro back. The paper stuff at Bunnings lasted a few seconds (essentially the paper fell apart)and cost twice as much. Stripped it all the way back. Then feed as much lineseed oil until the the timber does not take anymore. You see, how it dries up in some places really fast. Then let dry a few weeks. Then do the water magic. How to make it stick, no idea, as oil repels water. But your chances increase if you let the timber dry thorougly. I did lineseed baset primer, oil based undercoat, then Solarguard. The oil stuff I left to dry a few weeks each. Water based can paint twice a day. Looks still pretty neat after 5 years.
Posted Saturday 8 Feb 2014 @ 9:43:36 am from IP # -
Hi Ankerre, The importance of mixing limewash to a thin, whole milk-like consistency cannot be overemphasized. Limewash made too thick may appear to cover better when first applied, but will surely crack and craze upon drying, especially in the recesses of rougher-textured substrates. Like any fine-quality surface coating, many applied layers of thinned material build up a superior and, hence, more durable
finish than fewer and thicker coats. Do not be tempted to thicken the mix. As a milk, limewash is superbly workable, easy to apply and very effective. Remember that the surface should be damp to allow for good absorbency.I would not be heavy sanding any of the paint - especially if it is 30 years old. high possibility of lead based paint use. Scrape as much of the flaking paint off, then 'key' the top layer of whats left. Then ensure it's well washed. The lime to be using is hydrated lime. Ensure correct safety procedures when using as it can burn skin and eyes....good luck.
Oh, the finish is beautiful when due process is achieved.Posted Sunday 9 Feb 2014 @ 4:03:39 am from IP # -
ankerre
MemberMorbo & Eamon, thanks both for your further contributions. We take the point re possible lead based paint and will be cautious. The height and length of the shed is such that it is not an easy task, so we do not envisage easily re-doing the work. So, am looking for a good solution that can offer say a 10 year cycle. So, the idea is to set up scaffold and thoroughly do each wall, perhaps using a spray gun if the limewash will work using such a device. Otherwise a 100mm brush will be the go although we imagine that the brush will leave lines / stop marks in the wash as the application will not be heavy enough to brush out the joins etc; is this right?
Assuming that we do follow recommendations and say build up 3-5 thin layers or applications of limewash, can it then be sealed - say with penetrol or similar? Would a light coat of linseed and turpentine (50/50) over the surface "seal", while also making the colour and the timber darker? Would a coating or two of PVA *& water do the job?
Posted Sunday 9 Feb 2014 @ 5:55:00 am from IP # -
When limewash is first applied, it is translucent. When it dries, limewash becomes opaque. As additional coats are applied, the coverage power and full beauty of the treatment becomes apparent. Keep the mix stirred while applying limewash with the brush. During application with the brush, use a scooping and swirling motion in the pail in order to keep the mix suspended. Work in sections that assure full coverage. Mark the last position on the wall by using a free hand to point to the next area to be covered. Apply the limewash liberally and work it well into the surface with strokes in many directions. Expect the limewash to splatter off of the brush and be rather messy. Drop sheets and masking should be used for areas that will not be covered by limewash.
Using something like a fence brush or similar large coverage brush is better. Like morbo said, a sprayer will clog up, whether you sue the best or the cheapest. Even if you do filter it before use. Painting it works it into the timber getting greater adhesion. The finish won't require sealing and if you do it may react with the finish, remember Limewash has a high ph which is bonus of the finish. Like all painting, work in sections so if you do get weather caught, you know where to start. Always work on the shaded side and start early as possible, not working in midday or low humidity... let us all know, before and after pics -thanks.Posted Monday 10 Feb 2014 @ 9:37:06 am from IP # -
we use limewash too .we love it . my tip is to make the lime putty well in advance of using it (weeks are fine ). put the hydrated lime in a bucket and add water (1:1 ratio).
buy yourself an agitator and use in a drill .after a few days minimum, it is ready to use, but best left for longer. mix with agitator and add whatever other ingredients you plan to use.
we juts add a tiny bit of off white cement and water, but as mentioned above you can add lots of other things .We tried adding some bondcrete ,which apparently makes it more durable but we did not like the glossy look it added .Posted Monday 10 Feb 2014 @ 10:36:25 am from IP # -
Hi Dave, thanks for the everyday input. This is helpful, yes the PVA (bondcrete) does tend to gloss up but also leaves a viewable skin on the surface. As ankerre was asking about the linseed oil, this tends to 'dull' down the 'brilliant white' of the finish. For the stirrer, yes a drill and my preference is something similar to http://www.ebay.com.au/bhp/paint-mixer .. I agree with you in respect to the extra time left 'soaking', gives greater quality to the putty.
Posted Friday 14 Feb 2014 @ 10:52:00 pm from IP #
