Ballast discolouration

14280 Views 37 Replies 16 Participants Last post by reddo, Dec 18, 2009

patrick draper

Discussion Starter · Feb 11, 2009

I have recently ballasted about 15m of track with grey stone ballast and PVA adhesive. I have now found that the ballast has dried a green tinge and whenever I add more PVA mixed with grey poster paint it just goes a deeper green. If I had any hair I would be tearing it out. I have tried spraying some of it with grey car paint, paining it with emulsion, emulsion and oil paint, emulsion and water paint and praying. I now have four tracks running through a cricket pitch. The baseboard is Sundela with brown undercoat and the layout is in my loft. Is it the wet damp air causing the problem?
Can anyone help, I am sure somone else must have had the same problem? I do not have the make of the ballast but it is from a reputable model shop.

1 - 20 of 38 Posts

ebaykal

· #2 · Feb 11, 2009

Patrick hi,

Can you find out the brand name of the ballast?
I too had that problem of discoloration. It was Woodland Scenics medium ballast. No matter what you do, it changes color when applied with the PVA/water/detergent/meths mixture. Decreasing the PVA amount cured it a bit but increased the setting time.

Baykal

patrick draper

Discussion Starter · #3 · Feb 11, 2009

I will ring up the model shop tomorrow and find out the manufacturer's name. It may well be Woodland Scenics. It is certainly a problem, I have tried some with no glue at all and even that looks green. Thanks for the reply.

Richard Johnson

· #4 · Feb 12, 2009

*** The problem is that PVA is slightly acidic and will react with some ballasts and minerals to change their colour. This is a fault in the ballast really as its intended application is as you are using it, and the Mfr should test before marketing.

Its not just ballast that can react to acidic glues... When I built my 4mm scale model of Turbomotive I was finalising detail the day before a modeling contest I intended to enter it in... I used real coal in the tender as always and tried a new glue I'd bought at a discount shop - imagine my horror when the whole coal load went a bright metallic emerald green.... really bright! This calmed down as it dried but remained looking like a dwarf emerald mine with sparkly green everywhere. A quick spray of black fixed it evebtually

Back to Ballast:

It is more common with real rock ballast than woodland scenics which is actually crushed nut shells, however the dye they use may be reacting with the glue.

Your fix is as follows:

either rip it up and do it all again... steering clear of cheap PVA and using a better quality glue OR copydex mixed 1/3 glue, 1/3 water and 1/3 meths.. even more meths/water thinner if its a heavy glue type.

Test a wee bit first.

Pre-wet the tidy ballast with a mist of Meths before dribbling on the Glue/Meths/water mix. Re-spray after dribbling on and it'll totally disapperar into the ballast.

Or:

Let it dry as is - totally - ie place a fan heater or just a fan so that it blows across the ballast and let it go for a very long time - then wait some more. Truly dry given what you have been doing is more than 48 hours, possibly a week total!

When its totally dry and cured, spray with a non water based paint, such as an auto undercoat or airbrushing gray undercoat, let dry thoroughly then wash over whatever stains you like, but do NOT use water based stuff - this will just reactivate the reaction.

Richard

See less See more

ebaykal

· #5 · Feb 12, 2009

...and just a word of advice, try to use ballast that the N scalers use, i.e; fine, not medium, even if its woodland scenics. Medium looks too coarse and unrealistic even for OO scale.

Richard any brands that you can recommend?

Baykal

Brian Considine

· #6 · Feb 12, 2009

Sorry to say that this is a problem with the ballast itself - it's not actually stone or granite it's a sand based material.

If you can crush it to almost dust with hardly any effort then it's sand based & will unfortunatly tend to discolour that you have had.

Richard Johnson

· #7 · Feb 12, 2009 (Edited by Moderator)

***Hi erkut

The best I have used is the C&L finescale ballast - and as you say, I use in a mix if 3 parts N to 1 part HO so to speak...
It is made from ground olive stones, so has none of the bad habits of sand or stone, all of which are susceptible to discolouration due to chemical issues.

Richard

patrick draper

Discussion Starter · #8 · Feb 12, 2009

Thanks to all for your replies, I am trying to remove it and redo it with a different brand, I have some Hornby Scaledale but it is very rough. I will try and get some of the C&L finescale ballast. It is a real pain to have to do it twice.

patrick draper

Discussion Starter · #9 · Feb 15, 2009

An update. I have removed some of the ballast, washed it and dried it and it is still showing green. I have taken a photo of it and it looks a beautiful grey, I shall have to think of a way to lighten the ballast and am going to try a white colour wash. I took the ballast outside in the sun and it still looks green so if it is a lighting problem for this ballast then I will have to remove it. I have tried anothet type, Hornby, and this looks O.K. but is very course. I am trying to source some C&L finescale ballast as recommended, if anyone knows where I can get it from please let me know.

Richard Johnson

· #10 · Feb 15, 2009

*** Here is the web link - they have excellent fast mail order

www.finescale.org.uk

Richard

patrick draper

Discussion Starter · #11 · Feb 15, 2009

Thanks for the link, I have ordered from them.

ebaykal

· #12 · Feb 15, 2009

Patrick Hi,

Which ones did you order? C1152 or C1154?
I'd really appreciate your views on it once it arrives.
I also wish to order.

Baykal

Peter Armond

· #13 · Feb 15, 2009

This is a problem that has been mentioned on a number of occasions in the past on forums and whether it is the ballast or the glue is debateable. If you can't paint it, or live with it then sadly you will need to start again.

I have about 60cm of double track where this has happened with grey fine stone. As it is in one corner and not too noticeable I accept it at present but may change it at some future date.
Have you tried adding some green scatter so it looks as though the weed killer has not been round? My example was from a small bag that I bought in UK about 5 years ago, and I think but cannot be sure it was gaugemaster. I have used the exactly the same brand of PVA with this as I have used with other ballast I have used. Fortunately my wife was adverse to me using her precious baggage allowance to bring back bags of stones, so consequently it was only about 250 grams.

I have subsequently used ballast purchased in South Africa produced by a South African Company SA Scenics. I have not been able to find it on my last couple of visits to South Africa but it was substantially cheaper than any band available in UK. Cheaper still (free) is sand from the beach at lake Kariba which I have also used on part of my layout after sieving through a tea strainer. This is courser than sea sand, much darker in colour, but finer than most ballast products. Neither of these has turned green so I suggest it may be the ballast you have used rather than the PVA.

See less See more

mikebiggles

· #14 · Feb 15, 2009

Hi

Never had the problem of my ballast changing colour after fixing with PVA, but have never been happy with the result so I always spray paint it withHumbrol matt dark earth which i think looks more realistic for the era I model i.e. 50s-60s.
You could of course paint it any colour you prefer or a mixture of colours.

Hope this helps Mike

PS if you try it mask the tops of the rails saves on cleaning them afterwards.

Richard Johnson

· #15 · Feb 16, 2009

*** After I had a problem with a strong reaction between real coal and PVA I did a lot of experimenting - Its most definately a reaction between the particular brand of PVA and the specific brand/type of /mineral ballast. Many ballasts are either dyed or made from natural rock products that have components that react with the chemicals in the glue.

Not all PVA glues are the same - in fact they can be very different. the base ingredient is the same but the fillers and additives vary a great deal between glue brands, as does the acidity of the glue.

I also suspect some less than high quality dyes are used on some ballasts, or that the dye is not properly "fixed" before its dried and packed.

regards

Richard

QUOTE (Peter Armond @ 16 Feb 2009, 06:05) <{POST_SNAPBACK}>Neither of these has turned green so I suggest it may be the ballast you have used rather than the PVA.

Richard Johnson

· #16 · Feb 16, 2009

Looking at your prototype and layout photo's from time to time I would use C1152 - light gray. The dark gray is a little too dark for what you want I think

Richard

QUOTE (ebaykal @ 16 Feb 2009, 04:04) <{POST_SNAPBACK}>Patrick Hi,

Which ones did you order? C1152 or C1154?
I'd really appreciate your views on it once it arrives.
I also wish to order.

Baykal

ebaykal

· #17 · Feb 16, 2009

Thanks Richard,

QUOTE (Peter Armond @ 15 Feb 2009, 22:05) <{POST_SNAPBACK}>..... Cheaper still (free) is sand from the beach at lake Kariba which I have also used on part of my layout after sieving through a tea strainer. This is courser than sea sand, much darker in colour, but finer than most ballast products. Neither of these has turned green so I suggest it may be the ballast you have used rather than the PVA.

I have also tried sands of various regions. No matter how fine you sieve them, they have siliceous quartz particles like glass and shines!
So probably will use them near a pond or river on the layout.

Baykal

Peter Armond

· #18 · Feb 16, 2009

QUOTE (ebaykal @ 16 Feb 2009, 14:09) <{POST_SNAPBACK}>I have also tried sands of various regions. No matter how fine you sieve them, they have siliceous quartz particles like glass and shines!
So probably will use them near a pond or river on the layout.

Baykal
That's true, not to mention ""Fool''s Gold"!

34030 Watersmeet

· #19 · Feb 17, 2009

Also had same problem with some ballast that turned green after a while. Recently did some more ballasting with some "fine ballast" from Modeler's Mate which I bought at a show. Having run out, I bought some Gaugemaster N scale ballast which looks right on my OO layout and was similar to the grey of the earlier application. Neither of the finer sized ballast has shown the "green problem". I glued it with 1 part pva to 4 parts water, with drop of washing up liquid, having first sprayed water on track from old empty windowlene type bottle. This all seems to have worked ok.

I think from observation that a piece of full sized ballast is about half the size of a hand on average and using a 4mm scale figure, a grain of n gauge ballast is about half the size of the model figure's fist - so the finer ballast seems about right.

hope this helps,

Bill

patrick draper

Discussion Starter · #20 · Feb 19, 2009

I have C1153 and C1155, I ordered fine scale as I was told the 4mm scale would be too course. I have tested it and the darker colour is a bit too dark for what I want, the C1153 is still a bit dark but is fine and GREY, like me. I shall use the darker in certain places such as loco stopping areas, engine shed and some sidings. The ballast is certainly firmly coloured as I tried to lighten a bit with bleach to test and it had no effect. The ballast comes in good size jars with screw tops. It is a pity I didn't start with it, it would have saved a lot of problems and time.

1 - 20 of 38 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.