I read all the prior messages about the subject. My dilema is that two contractors have different view points on the application of a sealer. The first guy wants to apply a sealer after sanding and then apply several coats of poly. The second one said if a sealer is applied the poly cannot be absorbed by the wood and will be subject to pealing and cracking. He suggests two coats of poly after sanding. One more thing, is it worth the the extra expense to put a third coat of poly?