Resin casting

[67A]

Hi all,

 

Has anyone got experience in producing resin castings? I saw a demonstration at an exhibition by Wynnstay Models which looked great, he gives you a fact sheet on request and a contact for supply of materials, expensive to begin with (unless someone knows different). I'm looking to construct several yards of retaining wall for my Bermuda Road MPD layout (see layout topics) I think resin is the way to go.

Any information or guidelines would be greatly appreciated.

cheers

mike

[Phil Traxson]

Hi all,

 

Has anyone got experience in producing resin castings? I saw a demonstration at an exhibition by Wynnstay Models which looked great, he gives you a fact sheet on request and a contact for supply of materials, expensive to begin with (unless someone knows different). I'm looking to construct several yards of retaining wall for my Bermuda Road MPD layout (see layout topics) I think resin is the way to go.

Any information or guidelines would be greatly appreciated.

cheers

mike

 

Mike,

 

Glad I inspired you to have a go, like a lot of demonstraters I don't get much feedback as to whether its worth while.

 

For supplies of materials it might be worth getting in touch with Phil Atkinson at "Hobby Holidays". I was tutor on a weekend resin casting course he ran in October and he was looking at supplying the resin and silicone moulding rubber in smaller quantities for the modeller.

There has been a small hiccup in supplies of the mould rubber as Amber Composites no longer supply this in small quantities. If you have the fact sheet amend the rubber supplier to

 

Canonbury Arts Ltd.

65, Halliford Street

London

N1 3HF

 

Their code for the rubber is CTM 20

 

As to making your walling, its a bit like a cookery book, first make your pattern! If its to be an arched style retaining wall a length of a couple of arches needs to be made, if its plain walling with buttresses make the buttresses as a separate casting to cover the joins in the lengths of plain walling. I find lots of photo's of the real thing are important here and take your time to get the pattern right, remember you are going to repeat this for your wall and any mistakes will be repeated too.

 

I use "Slaters" sheets of walling for this, they do a lot of varieties and one is almost bound to suit your application. Having cut it to the shape you want It needs fastening to a backing trimmed to the same shape to thicken it up to about 2 to 3mm for casting, this can be foamboard, cardboard or similar and any apertures on the edges need filling and sealing.

 

This pattern then needs fastening centrally onto a backing sheet made as a rectangle about 3 to 5mm larger than the pattern in length and width.

 

The edges of this backing sheet are the surrounded by strips sized to form an open top box about 3 mm deeper than the pattern. these edge strips must be sealed to the edge of the box very well as the rubber is very searching and will escape if it can, likewise the pattern must be sealed all round its edges or the rubber will creep underneath and you will destroy the pattern when you try to take the mould off.

 

After this it gets easier, mix the rubber as per its instructions and pour into your box over the pattern. If all is well 24hrs or thereabouts later you will be able to peel the set rubber of the pattern and a few hours later you can pour in your resin mix and produce your first wall section. After nearly 15 years of casting I still get a satisfaction buzz from taking out the first casting for a new item.

 

I'll stop there for the moment but please feel free to get in touch with me if you decide to go ahead and need more help.

 

Phil Traxson

[burgundy]

Mike

Rather than using resin, had you thought of using something like dental stone (my supply was bought years ago in the US but I am sure that there is a UK equivalent) for the castings? It does not stink the house out, you are less likely to be allergic to it and, for something like a retaining wall, it should be at least as suitable. Making the moulds will be the same, but, to my mind, the subsequent casting process is a lot easier (and domestically friendlier).

Eric

[Mike Bellamy]

Rather than using resin . . . . . It does not stink the house out, you are less likely to be allergic to it . . . . . the subsequent casting process is a lot easier (and domestically friendlier).

Remember that Phil has 15 years experience and if it did smell or cause allergies then he wouldn't be using it all day every day for his business. Are you sure you are talking about the same type of resin that he uses? I have helped on his trade stand at shows, sat next to him at numerous demonstrations and been in his workshop when he has been casting and never experienced any smell or problems with any skin reaction. You just have to follow the usual precautions you would when mixing any chemicals together - wear gloves and ensure there is adequate ventilation. It may be that your experience is based on a different type of resin.

 

Mike

[BobD]

Epoxy resins do smell, however, polyurethene resin is better to use.

 

You still have to use caution, as the previous post says.

[Phil Traxson]

Mike

Rather than using resin, had you thought of using something like dental stone (my supply was bought years ago in the US but I am sure that there is a UK equivalent) for the castings? It does not stink the house out, you are less likely to be allergic to it and, for something like a retaining wall, it should be at least as suitable. Making the moulds will be the same, but, to my mind, the subsequent casting process is a lot easier (and domestically friendlier).

Eric

 

The modern resins that I use do not stink the house out as Mike already knows having seen me demonstrating casting at exhibitions, that type went out of use for modelling 20 years ago, and they are out of the mould 25 minutes after casting them.

Phil T.

[67A]

Hi to all who have replied and especially to Phil for yet more instruction.

 

I was really impressed with Phil's demonstration but its a lot to take in and you don't want to hog the poor man all day (yes you do). I will say with a nose like mine I would have noticed any unpleasant smell but there was none and it was in an exhibition hall which no doubt would have emptied had there been any strange whiff's.

 

I had thought about dental plaster but again where do you get the supply and is it prone to damage? I know even less about this medium but have not discounted it.

 

I asked the manufacturers for an idea of quantity produced from their packs offered but they have not yet replied. For information the rubber mould pack is 25kg and costs £265. Quite an investment unless you plan to do a lot of mouldings rather than re-castings. The casting resin packs start at about £20 for 1kg, £70 for 4.5kg and £250 for 25kg.

 

Can I add that the feedback on RMWeb is without doubt a fabulous tool in itself, long may it continue.

 

I will give Canonbury Arts a call.

cheers

mike

[Nicktoix]

Another source of supplies is http://www.tomps.com

 

Nick

[jonhall]

Probably a bit far from the OP's current location, but I'll be resin casting at the StAlbans show in January and Ally Pally in March. I'm using Easyflo 60 resin from http://www.notcutt.co.uk/

 

Jon

[Red Devil]

I've just started using some stuff from here http://www.nigellawton009.com/PayPalCasting.html Not had enough time to do what I want to yet, few bits so far have been pretty good.

 

Very quick postal service and extremelly helpfull too. There's also some good stuff on youtube that's worth watching for hints and tips.

[Karhedron]

Would Plaster-of-Paris be suitable? I would guess it is probably a bit heavier and more brittle than resin but it is easy to work with.

 

Just as an aside, it you are looking for long sections of retaining walls have you considered the range from International models?

 

http://www.internationalmodels.net/acatalog/Main_Catalogue_Index_Retaining_Walls_40.html

[Phil Traxson]

Hi to all who have replied and especially to Phil for yet more instruction.

 

I was really impressed with Phil's demonstration but its a lot to take in and you don't want to hog the poor man all day (yes you do). I will say with a nose like mine I would have noticed any unpleasant smell but there was none and it was in an exhibition hall which no doubt would have emptied had there been any strange whiff's.

 

I had thought about dental plaster but again where do you get the supply and is it prone to damage? I know even less about this medium but have not discounted it.

 

I asked the manufacturers for an idea of quantity produced from their packs offered but they have not yet replied. For information the rubber mould pack is 25kg and costs £265. Quite an investment unless you plan to do a lot of mouldings rather than re-castings. The casting resin packs start at about £20 for 1kg, £70 for 4.5kg and £250 for 25kg.

 

Can I add that the feedback on RMWeb is without doubt a fabulous tool in itself, long may it continue.

 

I will give Canonbury Arts a call.

cheers

mike

Those quotes seem high to me, Canonbury do rubber in 1kg packs for just under £30 including £9.90 delivery and 5kg costs me £89.90including again £9.90 delivery, and I think you will find the resin costs are for 1kg of each component i.e.£20 for 2kg of resin total. Either that or I am getting very favourable rates!

 

If you see me doing demonstration casting feel free to talk to me for as long as you need, I'm sure anyone else who is seriously interested will either listen in or join in. The next two will be at the 7mm Narrow Gauge Association members day in Mickleover Community centre on the outskirts of Derby on the 22nd of January 2011(day membership is available) and then Stafford Model Railway Exhibition at the County Show Ground, Stafford on the 5th/6th February 2011. Please come and introduce yourselves if you are at either of these, as the notice on my stand says"I feel lonely and unwanted if you don't speak to me", even if I look like I'm concentrating on the job in hand still speak to me, all demonstraters expect there scrap rate to rocket at exhibitions.

 

Phil T.

[jonhall]

I think you will find the resin costs are for 1kg of each component i.e.£20 for 2kg of resin total.

 

 

Something you need to clarify with each supplier, mine only sells their resin as a both-parts pack.

 

J

[67A]

Those quotes seem high to me, Canonbury do rubber in 1kg packs for just under £30 including £9.90 delivery and 5kg costs me £89.90including again £9.90 delivery, and I think you will find the resin costs are for 1kg of each component i.e.£20 for 2kg of resin total. Either that or I am getting very favourable rates!

 

If you see me doing demonstration casting feel free to talk to me for as long as you need, I'm sure anyone else who is seriously interested will either listen in or join in. The next two will be at the 7mm Narrow Gauge Association members day in Mickleover Community centre on the outskirts of Derby on the 22nd of January 2011(day membership is available) and then Stafford Model Railway Exhibition at the County Show Ground, Stafford on the 5th/6th February 2011. Please come and introduce yourselves if you are at either of these, as the notice on my stand says"I feel lonely and unwanted if you don't speak to me", even if I look like I'm concentrating on the job in hand still speak to me, all demonstraters expect there scrap rate to rocket at exhibitions.

 

Phil T.

 

Hi again Phil,

I will most probably be at Stafford and will indeed have a chat, It was Macclesfield show (i think) that I spoke with you this year. The prices I posted are what Amber quoted me this week. The rubber only comes in 25kg at £265 but following the above posts there are now further options.

 

Many thanks to all who have posted I have made plenty of notes and contacted some suppliers. I dont really want to buy in ready made walls as I like individuality and enjoy the scratchbuilding aspect.

cheers

mike

[Phil Traxson]

Hi again Phil,

I will most probably be at Stafford and will indeed have a chat, It was Macclesfield show (i think) that I spoke with you this year. The prices I posted are what Amber quoted me this week. The rubber only comes in 25kg at £265 but following the above posts there are now further options.

 

Many thanks to all who have posted I have made plenty of notes and contacted some suppliers. I dont really want to buy in ready made walls as I like individuality and enjoy the scratchbuilding aspect.

cheers

mike

Mike

I've had to change suppliers for my mould rubber since Amber upped their smallest size about a month ago, they were the ones who reccomended Canonbury Arts as an alternative supplier. I still think you were misinformed on the resin prices as it is almost exactly double what I pay and the two components of it are the same price, which is what makes me think you've been quoted for a pair. (I think they refer to it as a 'kit')

Its only a couple of months to Stafford so we can probably compare notes there.

 

Phil T.

[67A]

Mike

I've had to change suppliers for my mould rubber since Amber upped their smallest size about a month ago, they were the ones who reccomended Canonbury Arts as an alternative supplier. I still think you were misinformed on the resin prices as it is almost exactly double what I pay and the two components of it are the same price, which is what makes me think you've been quoted for a pair. (I think they refer to it as a 'kit')

Its only a couple of months to Stafford so we can probably compare notes there.

 

Phil T.

 

Just thought it manners to report that I have placed an order with Canonbury Arts for an initial trial batch of the required materials, the young lady (Eve) was very helpful and factsheets etc. will be included, good customer service. I'll let you know how I get on.

If I'm successful I'll bring a section to Stafford

cheers

mike

[Chinahand]

Just out of interest, does anyone know if it's possible to use the old 'Linka System' rubber moulds to make resin castings instead of the plaster ones they were originally intended for ??

[Phil Traxson]

Just out of interest, does anyone know if it's possible to use the old 'Linka System' rubber moulds to make resin castings instead of the plaster ones they were originally intended for ??

 

Been there, tried it, no can do. The resin won't come out of the mould without destroying the mould. But if it is for your own use only you could sacrifice the mould to make a resin casting and then take silicone rubber moulds off the casting, or even spray a coat of primer over a plaster casting and take moulds off that.

 

Phil T.

[Chinahand]

Thanks Phil. I thought that might be the case.

 

Decisions, decisions, decisions

[jonhall]

Just out of interest, does anyone know if it's possible to use the old 'Linka System' rubber moulds to make resin castings instead of the plaster ones they were originally intended for ??

 

It works with Easyflo60, the guy who does the 'new' linka that was at Ally Pally a couple of years ago lent me a mould whilst I was demonstrating. I don't know what the mould life would be like, because I only did the one cast, but the parts produced were really crisp.

 

Jon

[Phil Traxson]

It works with Easyflo60, the guy who does the 'new' linka that was at Ally Pally a couple of years ago lent me a mould whilst I was demonstrating. I don't know what the mould life would be like, because I only did the one cast, but the parts produced were really crisp.

 

Jon

 

Despite wrecking the mould, as you say Jon the detail is very crisp. I've just realised that despite the casting still being on the shelf it's been there best part of 10 years. Since then I've started using much improved resin and my techniques have improved too, maybe it's worth giving it another try just to see what happens. Obviously I woudn't be able to market it but it would be interesting to find out.

 

Phil T.

[dave1905]

Silcone RTV is probably the best material for urethane resin casting.

 

The key is to get a good master because EVERY surface detail will be copied. Ome master had some MEK that seeped out of a joint and left a small sheen on the plastic. When the castings were made, you could see the sheen marks on the castings.

 

RTV rubber has different degrees of hardness. If your castings have undercuts or a lot of deep relief, a softer RTV might be more useful.

 

With resins, a key consideration is 'pot time', the time it takes for the resin to set. Faster resins may set up in a minute or less, I prefer those with 3 minute or longer. That allows me to get the resin into the mold and work any bubbles out of the cracks. I have found that buying a plastic syringe is useful to "squirt" resin into thin crosssection areas and corners.

 

Urethane resins tend to be less stinky, with less viscosity and faster set times. Epoxy resins tend to be thicker, stinkier and have much longer set times.

 

If you are using a pressure chamber to cure your castings, urethane resins will do well with 40-50 psi, and epoxies need 70-80 psi. I use a gallon 'paint pot' as a pressure chamber because I cast one piece railcar shells and I get much better results (fewer bubbles and voids) in the complicated molds.

 

I have made flat molds and "squish" molds. I use flat molds to make underframes for rail cars and squish molds to make one piece rail car bodies. Squish molds have a frame that holds the mold halves, there is a female mold that the resin is poured into and then the male mold is inserted, "squishing" the resin between the two molds. After the resin cures the male mold is removed, the casting can be removed from the female mold. I end up with a boxcar shell or a gondola floor and sides, all in one piece.

 

A critical part of the process is temperature. If you chill one or both of the resin components it will lengthen the pot life. Once you get the resin in the mold if you heat it gently (I just shine a flood light on the molds) it will set up faster and cure thin sections better. Some of my gondolas have sides that are 14 mm (4 HO ft) high and only .1 mm (.040") thick.

 

Here is my squish mold with a car casting on it:

 

Here is a finished gondola with a cast resin boxcar behind it (the P&R car).

 

Here is a clas NMa caboose with a cast resin roof on a commercial model bobber caboose.

[scanman]

Mike

 

For all types of moulding & casting materials, check out the 'Alex Tiranti' website:-

 

www.tiranti.co.uk

 

I do some resin casting - including the new quayside walls for 'Penhallick'. They were cast in resin at Mel Rees's request - but I also use the same mould to produce them in plaster. For that I use 'Modell' - a fine dental casting plaster from Tiranti's. It has the advantage of having a reasonable intrinsic strength, unlike 'Plaster of Paris' - and a 'cure time' of about 15 minutes. The other advantage over using resin is that the proportions of resin to catalyst have to be pretty precise - I use a scale that measures in 0.1 gm increments... No such problems with plaster! (Oh yes - and plaster works out cheaper!)

 

When making retaining walls - particularly in a stone finish - beware of the dreaded 'repeat'! My walling masters are cast as plain blocks in 'modell' which are then hand-scribed in 6" lengths - I make them up in packs of three so the repeat comes every 18". You can also create curved sections - see my website at www.clearsolutions.me.uk' - the castings section. Note - this is not an 'ad' - if you want to know how I curved the section, let me know!

 

I guess the hardest part of the project is actually making the decision to start it

 

Regs

 

Ian B

 

 

[Phil Traxson]

Mike

 

For all types of moulding & casting materials, check out the 'Alex Tiranti' website:-

 

www.tiranti.co.uk

 

I do some resin casting - including the new quayside walls for 'Penhallick'. They were cast in resin at Mel Rees's request - but I also use the same mould to produce them in plaster. For that I use 'Modell' - a fine dental casting plaster from Tiranti's. It has the advantage of having a reasonable intrinsic strength, unlike 'Plaster of Paris' - and a 'cure time' of about 15 minutes. The other advantage over using resin is that the proportions of resin to catalyst have to be pretty precise - I use a scale that measures in 0.1 gm increments... No such problems with plaster! (Oh yes - and plaster works out cheaper!)

 

When making retaining walls - particularly in a stone finish - beware of the dreaded 'repeat'! My walling masters are cast as plain blocks in 'modell' which are then hand-scribed in 6" lengths - I make them up in packs of three so the repeat comes every 18". You can also create curved sections - see my website at www.clearsolutions.me.uk' - the castings section. Note - this is not an 'ad' - if you want to know how I curved the section, let me know!

 

I guess the hardest part of the project is actually making the decision to start it

 

Regs

 

Ian B

 

 

The resins I have used over the past few years have all been low viscocity, fast setting with a "pot life" (time allowed from mixing to getting in the mould) of 2 to 3 minutes,there is still time after this to work out any trapped air in the mould details, but most importantly the resin to catalyst mix is 50/50 ish, a Slight variation either side makes no difference to the quality. This is where it pays to go to a specialist supplier rather than a general one, they will advise you on the best types of resin and rubber to use for the job in hand. The only reason for changing resins has been for a better performance, again as advised by my supplier (and sometimes they were cheaper as well, double bonus!).

 

 

Phil T.

[Phil Traxson]

Silcone RTV is probably the best material for urethane resin casting.

 

The key is to get a good master because EVERY surface detail will be copied. Ome master had some MEK that seeped out of a joint and left a small sheen on the plastic. When the castings were made, you could see the sheen marks on the castings.

 

RTV rubber has different degrees of hardness. If your castings have undercuts or a lot of deep relief, a softer RTV might be more useful.

 

With resins, a key consideration is 'pot time', the time it takes for the resin to set. Faster resins may set up in a minute or less, I prefer those with 3 minute or longer. That allows me to get the resin into the mold and work any bubbles out of the cracks. I have found that buying a plastic syringe is useful to "squirt" resin into thin crosssection areas and corners.

 

Urethane resins tend to be less stinky, with less viscosity and faster set times. Epoxy resins tend to be thicker, stinkier and have much longer set times.

 

If you are using a pressure chamber to cure your castings, urethane resins will do well with 40-50 psi, and epoxies need 70-80 psi. I use a gallon 'paint pot' as a pressure chamber because I cast one piece railcar shells and I get much better results (fewer bubbles and voids) in the complicated molds.

 

I have made flat molds and "squish" molds. I use flat molds to make underframes for rail cars and squish molds to make one piece rail car bodies. Squish molds have a frame that holds the mold halves, there is a female mold that the resin is poured into and then the male mold is inserted, "squishing" the resin between the two molds. After the resin cures the male mold is removed, the casting can be removed from the female mold. I end up with a boxcar shell or a gondola floor and sides, all in one piece.

 

A critical part of the process is temperature. If you chill one or both of the resin components it will lengthen the pot life. Once you get the resin in the mold if you heat it gently (I just shine a flood light on the molds) it will set up faster and cure thin sections better. Some of my gondolas have sides that are 14 mm (4 HO ft) high and only .1 mm (.040") thick.

 

Here is my squish mold with a car casting on it:

 

Here is a finished gondola with a cast resin boxcar behind it (the P&R car).

 

Here is a clas NMa caboose with a cast resin roof on a commercial model bobber caboose.

Some nice castings there and you managed the description better than I can as well. Like you I found every single mark is reproduced, I had some patterns given to me with reference numbers written in felt tip marker, held in the right light every one could be read on every casting, of course they disappear with the first coat of primer as they are really only slight surface texture differences.

 

Phil T.