Think & Tinker, Ltd.
P.O. Box 1606, Palmer Lake, CO 80133
Tel: (719) 488-9640, Fax: (866) 453-8473
Sales:, Support:

SkypeMe at
SolderOn Lead

If you have not done so, please read the "DOs and DON'Ts section now.

Equipment Required:

  • Titration flask (125 ml)
  • 10 ml Automatic pipette
  • Digital titrator
  • 1 mL syringe
  • 0.5g and 1.0g measuring spoons

Reagents Required:

  • CDTA, 0.800M titration cartridge
  • pH 6.00 buffer powder pillows
  • Hexamethylenetetramine
  • Hydrogen peroxide, 30%, ACS
  • Methylthymol blue indicator powder pillows
  • Rochelle salt


  1. Using the syringe, measure 5 mL of bath into the 125 mL flask. Add approximately 45 mL of deionized water.
  2. Using the 0.5 g measuring spoon, add 1 spoonful of Rochelle salt and swirl to dissolve.
  3. Add 1 mL of 30% hydrogen peroxide and swirl gently to thoroughly mix. Wait approximately 1 minute to allow the peroxide to oxidize the dissolved tin.
  4. Using the 1 g measuring spoon, add 1 spoonfil of hexamethylenetetramine to the sample and swirl to dissolve.
  5. Add the contents of 1 ea. PH 6.0 buffer powder pillow and swirl to dissolve.
  6. Add the contents of 1 methylthymol blue powder pillow and swirl to dissolve. The sample solution should now be blue.

    If the sample does not turn blue, the pH is too low. Add an additional 1 g spoonful of hexamethylenetetramine before proceeding.

  7. Titrate the sample with CDTA solution to a straw-yellow endpoint. Record the number of digits (NUMLEAD) needed to reach the endpoint.
  8. To determine the concentration of dissolved lead (Pb metal), use:

    Pb (metal) = NUMLEAD x 0.0414 g/l


    Pb (metal) = NUMLEAD x 0.00553 oz/gal

  9. Assuming that you are using LeaRonal SolderOn Lead Concentrate (SLC) with 450 g/l lead metal and want to operate your bath at the optimum point of 11g/l of lead metal, the amount needed to replenish the 38 liter (10 gallon) bath is given by:

    SLC needed = (266 - NUMLEAD) x 0.0035 liters


    SLC needed = (266 - NUMLEAD) x 0.00092 gal.

    The acceptable range of digital titrator readings is:

    Acceptable Range Pb metal: 9.0 to 13.0 g/l
    NUMTIN: 217 to 317

Always wear protective clothing, acid resistant gloves, and a full coverage face shield
when handling this or any other corrosive material.

Established 1990

On the web since 1994

Sales: 1-(719) 488-9640    Tech Support: 1-(719) 488-9640    Fax: 1-(866) 453-8473
Copyright © 1994 - 2014 Think & Tinker, Ltd.