Idaho's Pool and Spa Remodeling Specialists
Preparation for New Interior Finish
As with any project, the devil is in the details.  When considering a pool or spa remodel one of the most important steps is preparing the existing pool or spa for the new finish. For interior surface renovations, two main methods of preparation exist; plaster chip out or bond coating.  Both have their advantages and disadvantages and we are here to help you understand the risks and benefits to each.
Stripping or Plaster Chip Out-  As the name implies, this is the removal of the finish from the pool.  Generally plaster chip out includes removal of the waterline tile as well.  This is usually done with small jackhammers where the operator hammers through the plaster to the gunite structure.  Once the pool structure is reached, the operator guides the jackhammer along the surface of the shell chipping out the plaster while minimizing the damage to the pool structure itself.  Once the old finish is removed, it is hauled away to the dump.  The structure is pressure washed and installation of the new finish can begin shortly thereafter.

     Pros and Cons of the Stripping Process
1. (Pro) Finish  removal exposes the shell so repairs of shell defects are more easily repaired.
2. (Pro) The new finish has a known sound surface to be applied to.  Delamination of the interior would bean an application error or faulty materials were installed.
3. (Con) Stripping a pool is a noisy, dirty process that can take several days to accomplish. 
4. (Con)  Stripping, or plaster chip out, is generally more expensive due to the additional investment of labor and need to haul away the material.
5.(Con) Removing the finish with jackhammers can weaken the pool structure.  In some instances, less experienced operators have punched holes through the structure leading to expensive and time consuming repairs to the structure.
6. (Con) A stripped or chipped out surface is usually not as smooth as one that is not chipped out.   To fill the "valleys" caused by the stripping process additional material must be used.  This can mean a more expensive finish.

Bond Coat-  is a coating of material that assures adhesion of the new interior finish during the pool remodel.  The process still requires some chip out, but it is limited to tile lines, around return fittings and suction fittings.  If waterline tile is not being removed, the plaster is cut right below the tile with a diamond blade saw.  For several inches below this cut, the interior finish is chipped away to allow for the new finish to be feathered into the tile without becoming too thin.  The same process applies to return fittings, suction ports and other features not being removed or renovated.  After this the interior finish is "sounded" with hammers.  This exposes any "hollow" spots in the finish, and those areas are removed.

Once the demolition phase is completed, the interior finish is pressure washed and cleaned thoroughly.  Depending on the bond coat manufacturer's directions, this may include an acid wash and neutralization followed by another pressure washing.  After the surface is cleaned, the bond coat material is applied.  Again, depending on manufacturer, this may be applied with a roller of sprayed on.  After the manufacturer's recommended cure time, the new finish is applied.

     Pros and Cons of the Bond Coat Process in a Pool Remodel
1. (Pro) Manufactured bond coats applied by manufacturer trained applicators have a warranty backed by the manufacturer.
2. (Pro) The process is generally less expensive due to less labor needed to prepare the pool or spa for refinishing.
3. (Pro) Bond coating is less destructive and the chances of harming the pool structure are minimized.
4. (Pro) Resurfacing is usually quicker than stripping the interior finish. 
5. (Con) The new finish is only as sound as the most sound previous layer.  If one of the previous layers fails for whatever reason, the new finish will be at risk of doing so.  This is why the sounding process by experienced and trained craftsman is so critical.
6. (Con) Homemade bonding materials do not carry a warranty, have not been tested and have not training requirements.  Be sure to know material is being used and if it is suitable for use in swimming pools and spas.

Articles on Stripping and Bond Coating
Pool and Spa News- Forming a Bond
Pool and Spa News- Chipping Away