Coal Trials – Diary Sheet Update

Coal Trials – Anecdotal Diary Sheet
High Level Feedback.

Update from Tom Attwood

The Anecdotal Diary Sheets have been running for three months and there has been a good response allowing sufficient feedback to now be given. The Diary Sheets are still active and further feedback is encouraged, including coals which have not featured heavily so far.

More detailed feedback will be given on the commonly featured fuels in the coming weeks. Please consider this update as an introduction or highlights of the Diary Sheet responses so far.

Ffos-y-Fran has been treated as the comparator for this data, a score like Ffos-y-Fran (88% overall) is considered a fuel that is performing with merit in road steam applications. The score shown is against the 8 questions shown in the table. It does not cover all possible variations, characteristics, likes/dislikes of the various fuels but is there to address what was considered to be key factors for the purpose of comparing and selecting a suitable alternative in the absence of Ffos-y-Fran.

The table below shows the eight questions, the 13 fuels which have had Diary Sheet response recorded, the average score given (shown in the green bars visually representing the score) and the overall Total % achieved by the fuel. Ffos-y-Fran is shown at the top as the comparator. Some of the data is also shown in a Spider Diagram at the end of this update, if you prefer.

The scoring criteria used is, 1 = very poor/No, through to 5 = Totally acceptable/Yes.


Newburn, Wildfire, Ecoal50 and Trevithick are all manufactured ovoid fuel products which have received multiple Diary Sheet responses. It should be noted that Trevithick Welsh Steaming Ovoids (Hargreaves) and Ecoal50 (CPL), dominated the early stages of ovoid trials in road steam. In comparison to those trialled in the last 6-8 weeks, their performance has been more disappointing than would have been hoped for, with overall scores of just 59% and 63% respectively.

Newburn (M&G) and Wildfire (CPL) are both repeatedly finding favour in a range of road steam uses, from generating for rides with showman’s engines, through to roading in hilly terrain with road trains of up to 10 tons, with overall scores of 88% and 83% respectively. Whilst not perfect, they are appearing to be viable options in a range of uses.

A few trials have been carried out by mixing Trevithick Welsh Steaming Ovoids with coal, ranging from Scottish, Russian and Welsh in ratios of 50/50 or 40/60. In general, this seems to have improved the usability of these ovoids in road use but issues of eventual clinkering, high ash in the ashpan/clogging the grate are reported after a few hours in some cases. There may be merit in this approach for some users to extend coal stocks for example. Collectively, combining coal with Trevithick Welsh Steaming Ovoids has improved the overall score from 59 to 78%.

Although no Diary Sheets have been submitted on just Trevithick Ovoids in a steam rally type setting, some operators are suggesting that they are suitable for sedentary rally use, feedback on this would be appreciated as the season gets underway. However, captured within the Diary Sheets, they did not perform well for hard working showman’s engines generating at an event, with pressure difficulties, dead spots in the fire, excessive ash, smokebox debris/char and ash emitted from the chimneys being common issues.

Briteflame (CPL), Country Blend (Stafford – Ireland), Taybrite (CPL) and Homefire (CPL), are all further Manufactured Ovoids that have been trialled with feedback via the Diary Sheets. However, these products have only had 1 or 2 responses each. Their scores are still valid and provided here to advise but unlike the 4 discussed above, have not benefitted from trials across a range of engine types and uses. Further feedback is greatly encouraged.

Briteflame (CPL) has attracted attention as it has performed well in 2 separate and challenging road trips undertaken by 2 different steam tractors in hilly terrain with trailers. It is hoped to expand the range of engines that this product is trialled on in the coming weeks.

Holzkohle is a restaurant grade charcoal and was initially selected by the owner for the desire of a clean burning fuel to attend a non-steam focused, family-orientated event. This included a short road trip. Perhaps surprisingly, it performed the task very well and was adopted by a further event (along with Newburn) due to the clean burning nature.

Russian Coal, there are reasonable stocks of this with various merchants around the country which was sourced before the war in Ukraine began. An already known and used coal by some in road steam, it has performed well for the owner who completed the diary sheet with the feedback that it was excellent, a little smoky at first but cleared when going down the road.

Finally, Colombian Coal Trebles. Opinion on Colombian coal seems to vary extensively and no doubt in part down to the source mine quality of coal. However, from the Diary Sheet received it has performed extremely well for the owner. The comment of little and often firing being used to support the ability to burn cleanly. This engine was undertaking wood sawing.

In conclusion, a return of Ffos-y-fran supply would be very desirable for most of us. However, in a volatile and challenging market it is hoped that this information will help owners, operators and event organisers be able to make suitable selections of an appropriate alternative for their application.  

Some miniature owners have asked about manufactured ovoid sizes and if any manufacturers will make “scale” ovoids. One manufacturer is trialling a “scaled” ovoid which is approximately 40mm in maximum size. Whilst not assured it will be viable, it is being fully explored. A few miniature owners have found the need to break up the ovoids to allow an even fire, good results have then been attained in most cases.

Most full-size engine operators have reported a need for a deeper fire particularly when working an engine using a manufactured fuel. This may be useful information for some who are yet to use such a product, but it will be a case of trial and improvement as factors such as firebar spacing and design, height of bars in the firebox along with a multitude of other variables will likely change the requirements from engine to engine.

Further feedback via the Diary Sheets is encouraged, please.