Posted by: @kevin-turvey

Can anybody recommend a brand of inexpensive pore or grain filler for a mahogany like wood available here in the uk?

Danish Oil works well as a grain filler on Mahogany type wood if you apply as the instructions and let it harden well. Then wet sand back to bare wood and the oil has filled the grain pores. I’m doing this on a Sapele solid body at the moment which will have a natural oil finish. 
I can post photos when I’ve finished but I’m not sure if the picture quality will show the detail.

Sometimes fillers have to be scraped smooth and not sanded to avoid pulling out. Mark shows on some of his utube videos how to use old Stanley blades as scrapers.

Thank you for that tip

I have some Rustins worktop oil which I think is similar to danish oil so I will try that on a scrap piece of similar wood. I assume it going to take a long time to cure.

Do you wet sand back using the oil and the resultant slurry fills the pores and dries - is that what you mean?

What sort of finish are you aiming for?

I'm *guessing* that grain filling using an oil wouldn't work too well if you were then going to stain the guitar for example.

@kevin-turvey 

I should have explained better. After a few coats of oil I wet sand with oil and abrasive paper along the grain and let it dry. Then I wet sand with water making sure to keep the water clean and not get any build up on the paper as this causes marks on the wood. 

Once you get a flat dull finish all the way over then 2 or 3 light coats of oil as a top coat. The grade of paper needed depends on how rough the wood is and how much the oil raises the grain.

I think a stain could be applied after flatting and before final coats as long as it’s not the same solvent base as the oil. Danish is white spirit soluble so a water based stain should work , just don’t be to aggressive with the final oil coats.

My intention was to cover the filled surface with 1 coat of LIBERON sanding sealer, sand then stain followed by several coats of sanding sealer sanding in between, then spray with tinted nitro followed by clear coats of nitro.

Would the oil filler process be compatible with this?

@kevin-turvey 

I think it will work. I’ve used sanding sealer over Danish oil, but from what you describe using oil as a filler probably isn’t necessary. From memory Liberon sanding sealer is quite thick so it will act as a grain filler. Spray cans of sealer are much thinner than brush on sealer and don’t grain fill very much.

However it would do a test first with Liberon and nitro to make sure they are compatible as nitro usually needs a specific nitro sealer or it bubbles.

According to the Liberon website: Please Note: Liberon Spirit Sanding Sealer is only recommended for use with wax finishes. It is not compatible with wood oils, paints or varnishes.

So thank you for warning me about that!

I will need a cellulose sanding sealer then but I might omit that

@kevin-turvey 

This is a good sanding sealer that will work and is available easily on the internet at not too much cost. Danish oil does work under nitro but is a lot of hard work as a grain filler. 
Chestnut also do a non nitro acrylic sealer and top coat, so if you are buying make sure to get the correct one.

I might get the chestnut nitro sanding sealer as sanding sealer is recommended for underneath the top coat to stop the wood from absorbing to much top coat.

@kevin-turvey 

Yes you will waste a lot of top coat if you don’t seal first.

The instructions mention use only one coat, is this brush painting on or spray coating?

@kevin-turvey 

I think one coat of sealer should work for both as it’s thick but each piece of wood is different so instructions are not always 100% accurate. The important thing is to have a smooth mirror finish before you apply top coat.

You can wet sand with cellulose

Ah good advice, thank you.

In the past I have used nitro on alder wood without a sealing coat so this is new to me as I haven't worked with mahogany in this context.

Thank you for sharing this post