Does adding less FO really make a stronger candle?

[AudraT]

Hello all. I've read that adding less FO, and not more, can make the HT in your candle stronger? Is this true? For example, if 8% FO isn't strong enough, then you might get better results if you add 6% rather than 10%. When I was first starting out I tested this theory once or twice and I didn't find this to be true. I wonder what everybody else's experiences have been?

[TallTayl]

The short answer, it depends.  
retail fragrances are often so diluted that there’s not much to work with. Not all, but many… 

some fragrance elements are more cloggy than others.  Some more volatile. More of a cloggy, resinous base not like patchouli, vanillin, clove, allspice, etc will usually burn less well with more fragrance.

not all wick series, materials, etc. perform equally

not all waxes burn the same, and need different wick series to burn optimally. 

candles are a teetering balancing act.  Imagine sitting on a chair with multiple legs.  When some of the legs are different lengths than needed for the chair you will topple over or otherwise not sit stably. 
 

one example I remember vividly was glass glow palm wax with a lilac fragrance.  At 6% fragrance the candle didn’t burn at all despite wick choices that “should” have worked according to the charts.  I backed down to 2% fragrance and the tiniest wick in the preferred series burned so strongly I had to throw the candle outside and open up my windows. This was in the dead of winter in Chicagoland, mind you. And the candle was a tea light. Imagine a TEALIGHT being so strong it over scented an open floor plan house. We were gagging it was so strong.