Turning Tamiya Colors Gloss?

Their X-marked range is Glossy, the XF-marked range is flat.

Use the Glossy range if possible, makes the decaling easier.

You could in theory, to get a semi-gloss finish, by adding gloss varnish to the flat, but best avoided if poss.

(the XF-21 is used to make Gloss.... err Flat!)

You could use Hannant's Xtracrylics (if you can find them) aircraft acrylics as these are semi to glossy, depending on how you spray them.

You can get a semi-gloss finish with a flat paint by putting it down very wet.  Also, you can make a flat finish glossy by overcoating with a clear glosscoat. I believe Tamiya makes a gloss clear, doesn't it?

Just about every model paint company makes a clear gloss finish as well as teh standby Future/Klear floor polish. Lay down the flat, let it dry, coat with light clear coats until you get teh sheenyou want. MicroScale also makes a satin, a semi gloss, finish,

Is there a particular reason why you can't use Tamiya X-8 (Gloss) Lemon Yellow?

The XF Yellow is exactly the color I need with a slight tint of and orangy effect, Lemon Yellow is too bright.

I'm going to try adding Clear to the paint and see if it turns out the way I wanted, if not, then yes adding Future after is the only thing I can do,

Quando omni flunkus, mortati

There are those that use Future/Klear etc., as thinners/carrier for air-brushing, inc. me.

Buuuut.... ALWAYS mix in a separate container as it is easier to bin a bodged container than spending ages cleaning out goop from the a/b.

If you do want rubbery goop, try Tamiya & cellulose/lacquer thinners....